NEW ORGANIC COMPOUNDS HAVING OPIOID PROPERTIES

Abstract: New echiboline derivatives with opioid properties of formula (I), wherein R represents a hydrocarbon rest. These are made by dealkylating corresponding 6-alkoxy-9-methyl-10-substituted echibolines, thereby converting the 6-alkoxy group to a 6-hydroxy group, especially using boron tribromide as dealkylating reagent. Specific examples are 6-hydroxy-9,10-dimethyl-echiboline, 6-hydroxy-9-methyl-10-allyl-echiboline and 6-hydroxy-9-methyl-10-cyclopropylmethyl-echiboline. The compounds may be in free base or salt form, and be incorporated as active ingredient into pharmaceutical compositions. Also, the corresponding 6-alkoxy-9-methyl-10-substituted echiboline derivatives as useful novel intermediates, which may be be made from a 6-alkoxy-9-methyl-echiboline by (A) reaction with a reagent which introduces the desired substituent into 10-position or (B) acylating to introduce the substituent R-CO- into the 10-position and reducing the acyl group to RCH2-.

Description: TITLE: NEW ORGANIC COMPOUNDS HAVING OPIOID PROPERTIES. This invention relates to new organic compounds having opioid properties, and to methods for their production. It is known that eserol ine, a hydrolysis product of physostigmine, has analgesic properties approximately equipotent with morphine but it also retains undesirabl e anti- chol inesterase activity. Analogues of eserol ine have been described in 1982 by Barto ini et a , in Canadian Patent Specification No. 1,137,489, but without presentation of any supporting pharmacological data. We l known and potent analgesics include compounds having the mol ecu! ar skeleton of morphine with addition of a substituted 2-carbon atom bridge between the 6 and 14 carbon atoms in the morphine structure, but this modification of the structure stil ] has not taken away the high dependence 1 iabil ity. It appears to be very difficult to identify, in any compound which possesses valuable opioid properties akin to those of morphine, exactly what causes the highly undesirable properties of respiratory depression, vomiting and dependence liability commonly associated with morphine. The varied actions of morphine are mediated via a range of different types of receptors and it is be] ieved that a particular action (for example analgesia) may be mediated via one type of receptor while a different type of receptor mediates another action, for example dependence liability. These different types of opioid receptors exist in peripheral tissues which can therefore serve as "models" for assessing opioid activity. In this way, the action of a drug on the intestinal muscle of the guinea pig, for example, is indicative of analgesic activity in man. The spectrum of sensitivity of different types of receptors (the receptor "profile") in a range of isolated tissues towards various opioids can thus be used as an indication of differences in properties which are of importance in practical -use, for exarπple the degree of dependence 1iability. The existence of opioid antagonists at these receptors assist in the identification of novel mechanisms of drug action (i.e. receptor "profiles" that differ from morphine). It is therefore very important to find compounds which do have opioid properties including the desired features but with the less desirable features removed or diminished, i.e. opioid compounds which have a different receptor "profile" from that of morphine itsel f. We have now found that the opioid activity of eseroline can be retained to a substantial degree while the anti- cholinesterase activity appears to be substantia l reduced or even removed, by incorporating a bridge structure in the eserol ine ring system, namely a four-carbon atom bridge. Additional 1y, such compounds have opioid receptor "profi es" that differ from that of morphine and so are indicative of different qual itative actions in v vo, and offer an a] ternative to morphine. Thus according to our invention we provide new organic compounds having opioid properties, namely new echiboline derivatives which are 6-hydroxy-9-methyl-echibol ines with a hydrocarbon substituent of up to 4 carbon atoms in the 10- posit on. The compounds of this invention, being bases, form sal s with acids. According , the present invention includes the compounds in the form of the free bases or their salts, and the new compounds may be defined as new echibol ine derivatives having, in their free-base form, the structure of a 6-hydroxy- 9-methyl-echiboline with a hydrocarbon substituent of up to 4 carbon atoms n the 10-position. The hydrocarbon substituent at the 10-position may contain up to four carbon atoms, and is preferably of the structure R.CH2- wherein R represents a hydrogen atom or a hydrocarbon group of up to three carbons. When R is a hydrocarbon group, this may be for example a cyclopropyl group or an ethenyl group (CH 2 =CH-), so that the 10-substituent is corresponding y a cyclopropyl -methyl or an allyl group. When R is a hydrogen atom, the 10-substituent is a methyl group. These compounds are especially useful and convenient to make. Echibol ine is the trivial name which has been given by Fritz and Fisher (Tetrahedron, 1964, 2C_ y pages 1737-1753) to the base l,2,3,4-tetrahydro-9a,4a-(immoethano)-9H-carbazol e. The new compounds of this invention may therefore be defined alternatively as l,2,3,4-tetrahydro-6-hydroxy-9- methyl -9a, 4a-(imιnoethano)-9H-carbazol es with a hydrocarbon substituent of up to 4 carbon atoms in the 10-position. In particular, specific compounds we provide are:- (A) 6-Hydroxy-9,10-dimethyl -echibol ine, (B) 6-Hydroxy-9-methyl-10-al 1 yl -echibol ine, and (C) 6-Hydroxy- -methyl -10-cycl opropyl methyl -echibol ine. These may be alternatively named, respectively, as:- (A) l,2,3,4-tetrahydro-6-hydroxy-9,10-dimethyl -9a, 4a- ( iminoethano) -9H-carbazol e\ (B) l,2,3,4-tetrahydro-6-hydroxy-9-methy]-10-al lyl-9a,4a- ( iminoethano) -9H-carbazole, and (C) 1, 2, 3, 4-tetrahydro-6-hydroxy-9-methy 1 -10-cycl opropy methyl - 9a , 4a- ( iminoethano) -9H-carbazol e . According to our invention we al so provide a process for making the said new compounds of our invention, i.e. the 10- substituted 6-hydroxy-9-methyl -echibol ine derivatives, which comprises dealkylating a 6-al koxy-9-methyl -echibol ine having a hydrocarbon substituent of up to 4 carbon atoms in the 10- position and thereby converting the 6-al koxy group to a free 6-hydroxy group. The alkoxy group in the 6-position of the echiboline ring system may be a lower alkoxy group, i.e. one containing an alky] group of l to 4 carbon atoms, but the preferred alkoxy group is methoxy, in which case the method comprises the de- methyl ation of a 6-methoxy-9-methy 1-10- substituted echiboline, for example 6-methoxy-9,10-dimethyl -echibol ine. Thus according to our invention we also provide new echibol ine derivatives, useful as intermediates for making the opioid compounds of our invention, namel 6-alkoxy-9-methyl- echibol ine derivatives having a hydrocarbon substituent of up to 4 carbon atoms in the 10-position. The de-al kyl ation step, in which the al oxy group (especial l y a methoxy group) of the 6— al koxy— 9-methyl -10- substituted echibol ine is converted to a hydroxy group, thus producing the 6-al koxy-9 -methyl -10- substituted echibol ine, may be carried out by use of any de-al kyl ating agent which does not attack the rest of the mol ecu! e. The preferred reagent is a boron hal ide, for exampl e boron tribromide. The boron tribromide may be used for this purpose in the manner conventional for O-deal kyl ation, for e am l e in sol ution in a non-pol ar organic sol ent (for exampl e a hal ogenated al ane, most convenientl y dichl oro-methane or mixtures thereof ) under hot and anhydrous conditions (convenientl at 60 to 90 degrees C) , fol l owed by hydrol ysis by addition of water or by addition of a hydroxy compound, for exampl e an al kanol and convenient! y methanol . According to our invention we al so provide a process for making the new intermediate compounds (the 6-al koxy-9-methyl - 10-substituted echibol ines) which comprises reacting a 6- al koxy-9-methyl -echibol ine with a reagent which introduces the desired hydrocarbon substituent into the 10-position. ' Especial l y, the process for making the compounds is carried out using a reagent of the structure R-CH^-Ha] ogen, wherein R has the meaning above. Exampl es of the preferred reagents for this purpose incl ude al 1 yl bromide. According to our invention we al so provide a process for making the 6-al koxy-9-methyl -10-substituted echibol ines which comprises acyl ating a corresponding 6-a l koxy-9-meth 1 - echibol ine to form the'corresponding 6-al koxy-9-methyl -10- acyl -echibol ine and then reducing this 6-al koxy-9-methy 1 -10- acyl -echibol ine whereby the carbonyl group of the acyl group is converted to a methyl ene group. The acyl ation introduces the substituent R.CO- (wherein R has the meaning stated above) into the 10-position. Acyl ation may be carried out using conventional techniques and acylating agents, for example the acid hal ides or anhydrides derived from the carboxyl ic acid R.COOH. For exampl e the reaction may be formyl ation, in which case the product after reduction is the 10-methyl derivative (i.e. a 6-al koxy-9, 10- dimethyl -echibol ine). Alternatively, substituents other than methyl can be introduced into the 10- position, as for example by using cycl opropyl carboxyl ic acid anhydride or chloride to introduce the cycl opropyl carbonyl group (O^^CH ' 00- in o the 10-positιon and then reducing this to the cycl opropyl methyl group (CH2)2 CH * CH 2~* The 6-al koxy-9-methyl -echibol ine may be made by reduction of the corresponding (i)-9-methyl -6-al koxy-11-oxo-echibo] ine, for example (i) -9-methyl -6-al koxy-11-oxo-echibol ine. These oxo- compounds, which are cycl ic amides, can be made by a modification of the Fischer indol e reaction from N-alpha- methyl 4-methoxypheny 1 hydrazine and ethyl cycl ohexanone-2- acetate. This method is analogous to the method described by Fritz and Stock [Tetrahedron, ^6_, 5821-5829, (1970)] for the synthesis of the homologous compound 2-oxo-8-methyl -5-methoxy- 2,3-dιhydro-lH,8H-3a,8a-propanopyrrolo-[2,3,b]-indole from N- aJpha-methyl 4-methoxypheny 1 hydrazine and ethyl cycl opentanone-2-acetate. The ethyl cycl ohexanone-2-acetate can be made by the method described by Segre, viterbo and Parisi, [ J.Am.Chem.Soc, 7_9, 3503-3505 (1957)]. The N-alpha- methyl 4-methoxyphenyl hydrazine can be made by the method described by Spath and Brunner [Chem. Ber., _58_, 518-523 (1925)]. The (i)-9-methy]-6-alkoxy-ll-oxo-echibo] ines, for example (i)-9-methyl -6-al koxy-11-oxo-echibol ine, is then reduced so as to convert the carbonyl group at the 11-position of the echiboline ring to a methyl ene group. A suitable reagent for this purpose is any which can reduce the carbonyl of an amide to methyl ene, for example lithium aluminium hydride. According to our invention we al so provide a process for making a 6-alkoxy-9,10-dimethyl-echibol ine which comprises reduction of the corresponding 9,10-bis-formyl derivative of a 6-alkoxy-echiboline. The 9,10-bιs-formyl derivative of a 6-alkoxy-echiboline may be made by formyl ation of the corresponding 6-al oxy- echibol ine. Formylation may be carried out using conventional formyl a ng agents which formyl ate the imino groups of heterocycl ic compounds, but it is preferred to use acetic- formic anhydride (alone or in solution in a solvent, for example acetic acid). The acetic-formic anhydride may be made in pure form by the known reaction between sodium formate and acetyl chloride, or it may be made in impure form (though still effective for the purposes of this invention) by reacting together formic acid and acetic anhydride to produce acetic-formic anhydride in admixture with acetic acid. The 6-alkoxy-echibol ine may be made by the reaction of 4-a]koxy-phenylhydrazine with 2-(2-chloroethyl)-cyclohexanone. This reaction can be carried out at el evated temperature (especially at about 60 to 70 degrees C.) in solution in a polar organic solvent and is a modification of the Fischer indole synthesis. Examples of suitable solvents for this purpose include lower alkanols (by which we mean alkanols having up to four carbon atoms in the molecule) for example methanol , ethanol, and mixtures thereof. The reduction may be accomplished by any reagent which reduces the carbonyl group of the acyl group to a methylene group (for exam le reduces a formyl group to a methyl group) without attacking the rest of the molecule. The preferred reducing agent for the purpose is 1 ithium aluminium hydride. This may be used in conventional manner, most conveniently in an inert polar solvent, for example tetrahydrofuran. These processes are especial 1y convenient for making 6- methoxy-9,10-dimethyl-echiboline. The new 6-hydroxy-9-methy] -10-substituted echiboline derivatives may be made, stored or used as salts, especially in the form of pharmaceutically acceptable salts, for example the hydrochl oπde or hydrobromide. In some cases, it is found that the free bases are unstable or tend to be difficult to purify — possibly through a tendency of the product to oxidise in basic sol ution. Consequently, it s then preCerred Lo make (and also to store) the products as salts instead of as the free bases. Salts can be made direct! y, avoiding the necessity to 1 iberate the free base, for example by using boron tribromide as the de¬ alkylating agent convert the 6-alkoxy group to a 6-hydroxy group and allowing the hydrobromide (usually di-hydrobromide) to crystallise directly from the reaction mixture without basifymg the reaction medium and sol vent- extracting the free base. The resulting salt (for example hydrobromide) may be purified by recrystal 1 isation. This direct formation of the salt may be achieved simply by adjusting the solvent medium in which the reaction product is prepared so that the salt has a sufficiently low solubility to cause it to come out of sol ution. In the case of the boron tribromide deal kyl ation method, the variation can be to add an organic hydroxy compound (preferably an alkanol, and most conveniently methanol ) instead of water after deal kyl ation has taken place. This is especially applicable to the products in which the 10-substιtuent is unsaturated or cyclic, for example ally] or cycl opropyl methyl . The compounds of the invention may be used in man or animal s for their effects on opioid receptors of the peripheral and central nervous systems. For this purpose they may be used in the form of formulations containing the compound together with conventional adjuvants, diluents and the like as are suitable for enteral and parenteral administration. Accordingly the invention also provides pharmaceutical compositions comprising a compound as active ingredient. The invention is illustrated but not limited by the following Examples, m which parts and percentages are by weight unl ess stated otherwise. β PROCEDURES : Mel ting points were measured on a Kof 1 er hot stage apparatus and are uncorrected. Ul traviol et, infra-red, -1-H-nmr and mass spectra were recorded on a Perkin-El mer model 402 spectr ophotometer , a Pye Unica model SP3-100 spectro- photometer , either a Perkin-El mer model R12B 60-MHz or a Bruker model WP80 80-MHz spectrophotometer (TMS was used as internal standard) and a Kratos model MS-25 instrument connected to a DS-55 data output terminal , respective y. Ti c was performed using Pol ygram Al ox N/UV25 pl ates (0.2mm) suppl ied by Cam] ab, Cambridge. Col umn chromatography was effected upon Brockmann grade 1 al umina suppl ied by BDH. EXAMPLE 1. Preparation of (_)-9,10-Di-Methyl-6-Hydroxy-Echiboline:- A solution of boron tribromide (478 mg) in dichl oro- methane (5 ml) was added, in one portion, to a solution of (i)-9,10-di-methyl-6-methoxy-echibol ine (53 mg) in dichl oro- methane (5 ml ) cool ed to -78 degrees C. The mixture was allowed to warm slowl to ambient temperature over a period of 2 hours, and then boiled under reflux conditions for 1 hour, and then cooled again to ambient temperature. Then water (3 m] ) was added and the mixture was neutral ised by addition of sodium carbonate. The organic (dichloro-methane) phase was then separated and dried over anhydrous magnesium sulphate, and the solvent was removed by evaporation. The resulting product was a brown oil (42 mg, 83% yield). Physical properties measured were:- TLC (Ethanol/Chioroform, 1:9 by volume): R f = 0.63, (Compare R^ of the starting material , which is 0.86 under the same conditions), IR (Chloroform): 3280 cm -1 (broad) (OH), MS: m/e = 258 (100%) (M + ), 243 (5.7%) (M + -CH 3 ), 229 (5.9%), 201 (92.5%) [M + -(CH 2 )2 NC H 3 - The di-hydrochl oride crystallised from a mixture of ethanol and ether as pale tan prisms, melting point 205-207 degrees C. (with sintering from 184-186 degrees C). El emental anal ysis of the product gave the resul t:- Found: C 54.2, 54.1, 53.7; H 7.25, 7.4, 7.0; N 7.8, 8.9, 7.1; Cl 22.4. [C 16 H 23 C1 2 N 2 0 requires C 58.9, H 7.3, N 8.45, Cl 21.4%] 1 7.07 ppm. (lH d ) (H 5 ) (J me ta =4Hz); 7.00 ppm. (lH dd )H 7 (J 0 rtho= 11Hz ' J meta =4Hz )<- 3.90 ppm. (3Hs) (N 9 -CH 3 ); 2.42 ppm. (3Hs) (N 10 -CH 3 ); 3.25-1.37 ppm. (12Hm) (methyl ene envelope); MS: m/e = 258 (63.6%) (M + ), 243 (3.8%), • 229 (4.9%), 201 (100%). Preparation of intermediates for above:- Preparation of ( L)-6-Methoxy-Echiboline:- Equimolar proportions of 4-methoxy phenyihydrazine (2.76 g, 0.02 mole) [Frahn and Illman, Australian J. Chem., 1974, 27, 1361-1365] and 2-(2-chl oroethyl )-cycl ohexanone [Volodina, Kiryushkina and Terent'ev, Dokl . Akad. Nauk. S.S.S.R., 1965 162, (1), 90-93] (3.20 g, 0.02 mole) were dissolved in ethanol (20 ml) and the mixture was heated at boiling temperature under ref 1 ux conditions for 8 hours. The ethanol was then removed by evaporation, to leave a red-brown oily residue. This residue was digested with 0.1 molar aqueous hydrochloric acid (200 ml) at approximately 70 degrees C. to dissolve soluble material. The mixture was then cooled to ambient temperature and neutral acid-insol ubl e materials were removed by extraction " with di-ethyl ether. The aqueous acid layer was then basified by addition of sodium hydroxide, conveniently as solid caustic soda pellets, and the resulting gummy precipitate was extracted with chloroform (twice, using portions of 60 ml each). The chloroform extracts were combined and then dried by addition of anhydrous magnesium sulphate, the chloroform was removed by evaporation, and the residual dark brown oil was purified by column chromatography on a column of neutral alumina, using chl oroform as the carrier sol vent. The purified product was obtained as a brown oil which crystallised after standing for several days. It was recrystal 1 ised from petroleum ether (boiling range 60-80 degrees C. ) to form pale cream coloured crystals, melting point 88-89 degrees C. Elemental analysis of the product gave the result:— Found:- C 74.0; H 8.6; N il.7%. L "C 15 H 20 N 2° requires C 73.75; H 8.25; N 11.45%]. Physical properties measured were:— (3H m )(H,H 7 ,H 8 ); 3.75 ppm. (3Hs) (0CH3); 2.85 ppm. (2H b ) (CH 2 N); 2.40 ppm. (2H b ) (D 2 0 exchanged) (2xNH); 2.10-1.50 ppm. (10H bm ) (methylene envelope). MS: m/e = 244 (87%)(M + ); 201 (97%) (M + - CH 2 =CH.NH 2 ); 200 (100%) (M + - (CH 2 ) 2 NH 2 )- UV (in * MeOH):- X max 230 nm ( 1 og ζ = 4.02), 280 niti (1og £ = 3.85); Λ max 248 nm ( 1og = 3.89), 320 nm ( 1 og = 3.84). Preparation of (—)-9,10-Di-Formyl-6-Methoxy-Echiboline:- (Method A) A mixture of acetic anhydride (2 ml ) and formic acid (l m ) was heated at 50-70 degrees C. for 2 hours, and then cooled to 0 degrees C. and (JL)-6-methoxy-echibol ine (25 mg) was added with stirring, under anhydrous conditions. The resulting pale-brown solution was allowed to warm to ambient temperature, then water (50 ml ) was added and the mixture was neutralised by addition of solid sodium carbonate and then extracted with chloroform (three times, using 8 ml portions each time). The chloroform extracts were combined and washed with a saturated aqueous solution of sodium carbonate (10 ml), dried with anhydrous sodium carbonate, and then the chloroform was removed by evaporation. The residue was purified by column chromatography on a column of basic alumina, using a mixture (1:1 by volume) of chloroform and petroleum ether (boiling range 60-80 degrees C.) as the carrier solvent. This produced the bis- formyl derivative as a pale brown oil (22 mg, 71% yield). Preparation of (±)-9, lO-Di-Formyl-6-Methoxy-Echibol ine:- (Method B) A solution of acetic- formic anhydride (1 ml) in dichl oro- methane (2 ml ) was added dropwise under anhydrous conditions to a stirred solution of (i)-6-methoxy-echibol ine (123 mg) in dichl oro-methane (5 ml ) at 0 degrees C. with cooling. The mixture was then allowed to warm to ambient temperature and stirring was continued overnight. Then water was added and the di- formyl derivative was isolated in the same way as described in procedure (B.2) above, i.e. by extraction with chloroform. (133 mg., 88% yield). The properties of the products made by Methods A and B above were identical, namely:- TLC (Chloroform): R f = 0.26, IR (liquid film): Transparent between 4000 and 3100 cm -1 (no NH); 1660 cm -1 (C=0); MS: m/e = 300 (4.5%)(M + ); 272 (35%) (M + -C0); 200 (40%) (M + -CO-CH 2 =CHNHCHO). Preparation of (— ) -9, 10 -Pi-Methyl -6 -Methoxy-Echibo ine :- A solution of C_L)-9,10-di-formy]-6-methoxy-echibol ine (216 mg) in tetrahydrofuran (25 ml ) was boil ed under anhydrous reflux with lithium aluminium hydride (0.72 g) for 3 hours. The excess of 1 ithium al ummium hydride was then decomposed by dropwise addition of water and the suspended white sol id was removed by filtration and washed well with tetrahydrofuran. The combined fil trate and washings were combined and dried (using anhydrous sodium carbonate) and the tetrahydrofuran sol vent was removed by evaporation. The residue from the evaporation was purified by column chromatography on a neutral alumina column, using a mixture (1:1 by volume) of chloroform and petroleum ether (boiling range 60-80 degrees G.) as the carrier solvent, to provide the product as a pale brown o l (118 mg, 60% yield), boiling point 160-165 degrees C. at 0»01 mm Hg. Physical properties measured were:- TLC (60-80 petroleum ether :chl or o form, 1:1): Rf = 0.25, IR (liquid film): Transparent between 4000 and 3100 cm -1 and between 1800 and 1610 cm -1 (no NH or =C0); MS: m/e = 272 (98%) (M + ); 257 (9%) (M + - CH 3 ) ; 215 (100%) (M + -CH 2 =CH.NH.CH 3 ); 200 (20%) (215-CH 3 ). 1 H-nmr (CDCl 3 ); = 6.60 ppm. r (H 5 ,H 7 ); 6.15 ppm. (lH d ) (Hg ) 12 Hz ' ); 3.70 ppm. (3H S ) (0CH 3 ); 2.75 ppm. (5H S ) (N 9 -CH 3 /N 10 -CH 2 ); 2.40 ppm. (3H S ) (N 10 -CH 3 ); 2.00-1.30 ppm. (10H) (mul tip] et) (methyl ene envelope), UV (in MeOH): X max 255 n (log 6 = 3.95), 324 nm (log = 3.44), UV (in MeOH/HC ) \ max 247 nm (log = 3.81), 319 nm (log£ = 3.78). The base was al so characterised as its picrate, which was obtained from ethanol as yellow needles, melting point 149-150 degrees C. El emental anal ysis of the picrate gave the resul t:- Found:- C 54.9; H 5.5; N 13.9%. E C 23 H 27 N 5°8 requires C 55.1; H 5.45; N 13-95%]. The free base was ] iberated from the picrate by treatment with sodium hydroxide solution, extraction with chloroform, passage of the chloroform solution through a short basic alumina column and removal of the solvent, and had spectral data identical with those given above. EXAMPLE 2. ' Preparation of (±)-9,10-Di-Methy]-6-Hydroxy-Echiboline:- A solution of boron tribromide (2 g) in dichloro-methane (20 ml ) was added, in one portion, to a solution of ( L)-9,10- di-methyl-6-methoxy-echibol ine (0.2 g) in dichloro-methane (20 ml ) cooled to -78 degrees C. The mixture was al 1owed to warm slowly to ambient temperature over a period of 2 hours and then boiled under reflux for 1 hour and then cooled again to ambient temperature. Then water (12 ml ) was added and the mixture was neutralised by addition of sodium carbonate. The organic (dichloro-methane) phase was then separated from the aqueous phase and the aqueous phase was washed with chloroform (twice, using 20 ml portions each time). The organic phases were combined and dried over anhydrous magnesium sulphate and the solvent was removed by evaporation. The resulting product was a pale brown oil (0.182 g, 95.9% yield). The di-hydrochl oride was immediately prepared, crystal 1 ised from a mixture of ethanol and di-ethyl ether as pale tan prisms, melting point 207-209 degrees C. (with seating from 185-187 degrees C). Physical properties measured were:- MS: m/z = 258 (23-3%) (M + ), 201 (36..0%) (M + -CH 2 =CH-NH.CH 3 ); L H-nmr (D 2 θ): S = 7.50 ppm. (lH d ) (Hg) (J ortho =llHz) ; 7.02 ppm. (1H S ) (H 5 ); 6.95 ppm. (lH d ) (H 7 ) (J 0 rtho =11Hz ) • 3.89 ppm. (3H S ) (N 9 -CH 3 h 2.89 ppm. (3H S ) (N 1Q -CH 3 ); 3.3-1.0 ppm. (12H m ) (methyl ene envelope). Preparation of intermediates for above :- Preparation of (-t)-9-Methyl-6-Methoxy-ll-Oxo-Echibo ine:- A solution of 4-methoxy-N- alpha-methyl phenyl hydrazine (6.95 g) with ethyl cycl ohexanone-2-acetate (8.79 g) [Segre, Viterbo and Parisi, et al ., J.Am.Chem.Soc, 79, 3503-3505 (1957)] in benzene (sodium dried; 40 ml), with 3 drops of glacial acetic acid added, was boiled under reflux conditions emp] oying a Dean & Stark separator until no further water was separated (two hours). The benzene was then removed by evaporation leaving a red-brown oil residue to which glacial acetic acid (25 ml) was added. The mixture was boiled under reflux for 1.5 hours The acetic acid was the removed by evaporation, to 1 eave a brown oil y residue. This residue was dissolved in chloroform (500 ml). The chloroform solution was shaken with aqueous hydrochloric acid (6M) four times, using 200 ml portions each time. The hydrochl oric acid extracts were combined and ice (200g) added followed by strong ammonia solution (0.88) to achieve basification. The resultant solid was removed by filtration (3.8 g, 30.6% yield). The material recrystal 1 ised from methanol as pale cream plates melting point 227-229 degrees C. Physical properties measured were:- IR (KC1 disc): 1685 cm -1 (C=0); MS: m/z = 272 (100%) (M + ), 257 (26.5%) (M + -CH 3 ). 1 H-nmr (CDC1 3 ): £ = 6.75 ppm. (lH d ) (H ? ) ,(J ortho = 12 Hz); 6.65 ppm. (1H S ) (H 5 ); 6.40 ppm. (lH d ) (Hg) (J ortho = 12 Hz); 3.75 ppm. (3H S ) (OCH 3 ); 2.70 ppm. (3H S ) (Ng - CH 3 ); 2.60 ppm. (2H S ) (N 10 -CO-CH 2 ); 2.10-1.20 ppm. (8Hg M ) (methyl ene envelope). Elemental analysis of the product gave the result:- Found:- C 70.3; H 7.6; N 9.9%. E C 16 H 20 N 2°2 reo i uires 70.7; H 7.4; N 10.3%]. Preparation of (±) -6-Methoxy-9-Methyl -Echibol ine: - A solution of (±.)-9methyl -6-methoxy-ll-oxo-echibol ine (2.81 g) in tetrahydrofuran (500 ml ) was added with stirring to a suspension of lithium aluminium hydride (1.51 g) in tetrahydrofuran (100 ml). The mixture was boiled under anhydrous reflux for 16 hours. The excess of lithium aluminium hydride was then decomposed by dropwise addition of a saturated aqueous solution of sodium sulphate and the suspended white solid was removed by fil ration and washed with di-ethyl ether The organic phase was separated and the aqueous phase shaken with di-ethyl ether (three times, using 100 ml portions each time) The organic phases were combined and dried (using anhydrous magnesium sulphate) and the solvent was removed by evaporation. The resulting product was a brown oil , (2.12 g, 74.4% yield). Physical ' properties measured were:- IR (liquid film): 3300 cm- 1 (broad) (N-H), Transparent between 1800 and 1610 cm -1 (no =C0); MS: m/z = 258 (56.7%) (M + ); 243 (12.4%) (M + - CH 3 ); 228 (16.2%) (243 - CH 3 ) ; 215 (27.8%) (M + -CH 2 =CH.NH 2 )- ^-H-nmr (CDCI 3 ) ; S = 6.60 ppm. (2H m ) (H 5 and H 7 ) ; 6.20 ppm. (lH d ) (Hg ) (J ort o = 12 Hz ) ; 3.75 ppm. (3H S ) (OCH 3 ) ; 2.81 ppm. (2H S ) (N 10 -CH 2 ) 2.65 ppm. (3H S ) (Ng - CH 3 ) ; 2.1-1.2 ppm. (llH 6m ) (methyl ene envel ope and N-H (D 2 0 exchanged) . The base was al so characterised as its picrate which was obtained from ethanol as yel l ow-orange needl es, mel ting point 170-172 degrees C. El emental analysis of the picrate gave the resul t:- Found: - C 54.6; H 5.4; N 14.6%. ^ C 22 H 25 N 5°8 requires C 54.2; H 5.2 ; N 14.4%] . The free base was 1 iberated rom the picrate by treatment with sodium hydroxide sol ution, extraction into chl oroform, passage of the chl oroform sol ution through a short basic al umina col umn and removal of the sol vent, and had spectral data identical with those given above. Preparation of ( L)-9-Methyl-10-Formy]-6-Methoxy-Echiboline:- A solution of acetic- ormic anhydride (6 ml) in dichloro- methane (10 ml ) was added dropwise under anhydrous conditions to a stirred solution of (+)-9-methyl-6-methoxy-echibol ine (0.613 g) in dichloro-methane (20 ml) at 0 degrees C. with cooling. The mixture was then allowed to warm to ambient temperature and stirring was continued overnight. Then water (50 ml) was added and the mixture was neutral ised by addition of solid sodium carbonate and then extracted with chloroform (three times, using 20 ml portions each time). The chloroform extracts were combined and washed with a saturated aqueous solution of sodium carbonate (50 ml), dried with anhydrous sodium carbonate and the organic sol vent was removed by evaporation, to give a brown oil (0.662 g, 91.5% yield). Physical properties measured were':- IR (1 iquid film): Transparent between 4000 and 3100 cm~l (no NH); 1660 cm ""! (no =CO); MS: m/z = 286 (100%) (M + ); 271 (20.4%) (M + - CH 3 ); 215 (41.0%) (M+-CH 2 =CH.NH.CH0); 1 H-nmr (CDCI3); $ = 8.4 ppm. (1H S ) ( -CHO); 6.65 ppm. (2H m ) (H5 and H 7 ); 6.30 ppm. (lH d ) (Hg) (J 0 rtho =12 Hz ) * 3.74 ppm. (3H S ) (OCH3); 2.70 ppm. (3H S ) (Ng - CH3); 2.30-1.10 ppm. (12H m ) (methyl ene envelope). Preparation of (-!l)-9 , lO-Di-Methyl-6-Methoxy-Echibol ine:- A solution of (_t)-9-methy] -10- formyl -6-methoxy- echibol ine (0.60 g, 0.002 mole) in tetrahydro uran (50 ml ) was heated at boiling temperature under anhydrous reflux conditions with lithium aluminium hydride (0.70 g, 0.019 mole) for 3 hours. The excess of 1 ithium al uminium hydride was then decomposed by dropwise addition of a saturated aqueous solution of sodium sulphate, and the suspended white solid was removed by filtration and washed well with di-ethyl ether. The organic phase was separated and the aqueous phase shaken with di-ethyl ether (three times, using 100 ml portions each time). The organic phases were combined and dried (using anhydrous magnesium sulphate) and the sol vent was removed by evaporation, to give a brown oil, (0.36 g, 62.1% yield). Physical properties measured were:- IR (liquid film): Transparent between 4000 and 3100 αrT 1 , and between 1800 and 1610 cm -1 (no NH or =Cθ); MS: m/z = 272 (70.2%) (M + ); 257 (8.3%) (M + - CH 3 ); 215 (84.3%) (M + -CH 2 =CH.NH.CH 3 ); 200 (18.3%) (215 - CH3); . (2H m ) (H 5 , H ? ) ; 6.20 ppm. (lH d ) (Hg ) (J ortno = 1 Hz ) ; 2.76 ppm. (5H S ) (N 10 -CH 3 , N 10 -CH 2 ) ; 2.43 ppm. ( 3H Ξ ) (Ng - CH3 ) ; 2.30-1.25 ppm. (10H m ) (methyl ene envel ope) . The base was further characterised as its picrate, which was obtained from ethanol as yel l ow need l es , mel ting point 151-155 degrees C. (Literature val ue 149-150 degrees C) . EXAMPLE 3. Preparation of ( l)-9-Methyl-10-Cyclopropylmethyl-6-Hydroxy- Echiboline:- A solution of boron tribromide (0.658 g) in dichloro- methane (2.6 ml ) was added dropwise, over a period of 30 minutes, to a stirred solution of (±.)-9-methyl -10- cyclopropylmethyl-6-methoxy-echibol ine (0.2 g) in dichl oro- methane (4.6 ml) cooled to 1 degree C. The mixture was allowed to warm to ambient temperature over a period of 2 hours and then it ' was partial ly concentrated by solvent evaporation. The mixture was then chilled to 0 degrees C. using an ice bath, and methanol (1.5 ml ) was added dropwise. After stirring the cooled solution for 15 minutes ethyl acetate was added to afford a pale yel low crystal line material (0.213 g, 72.2% yield) of the desired compound as its di- hydrobromide salt, melting point 193-195 degrees C. The compound was recrystal 1 ised from a mixture of methanol and ethyl acetate. Physical properties measured were:- MS: m/z = 298 (12.8%) (M + ), 243 (2.6%) 214 (6.2%) 201 (52.4%) 1 H-nmr (D 2 θ): £ = 7.60 ppm. (lH d ) (Hg) (J 0 rtho =11Hz) ' 7.13 ppm. (lH d ) (H 5 ) (J me ta =4Hz) ; 7.03 ppm. (lH dd ) (H 7 ) (J ortho =llHz, meiLa =4Hz); 3.98 ppm. (3Hs) (Ng-CH 3 ) 3.2-1.3 ppm. (14H m ) (N 10 -CH 2 / N 10 -CH 2 / (methy 1 ene en ve ] ope ) ; 1.0-0.15 ppm. (5H m ) ( cycl opropyl ) . Elemental analysis of the product gave the result:- Found:- C 47.6; H 6.3; N 5.6; Br 34.7%. '- G 19 H 28 N 2 OBr 2 requires C 49.6; H 6.1; N 6.1; Br 34.7%] Preparation of intermediates for above: - Preparation of ( l)-9-Methy]-10-Cycl opropyl carboxy-6-Methoxy- Echiboline:- A solution of cycl opropyl -carboxyl ic acid anhydride (8 ml ) in dichl oro-methane (20 ml ) was added dropwise under anhydrous conditions to a stirred solution of (i) -9-methyl -6- methoxy-echibol ine (0.8 g) in dichl oro-methane (40 ml) at 0 degrees C. with cool ing. The mixture was then al 1 owed to warm to ambient temperature and stirring was continued overnight. Then chloroform (60 ml ) was added and the mixture was shaken with 3M aqueous hydrochloric acid (four times, using 50 ml portions each time). Ice (100 g) was added to the combined aqueous extracts and the solution was basified with strong aqueous ammonia solution (0.88) This mixture was shaken with chloroform (four times, using 50 ml portions each time). The chloroform extracts were combined, dried with anhydrous sodium carbonate and then the organic sol vent was removed by evaporation to give a brown oil (0.886 g, 87.7% yield). The material crystal 1 ised on standing. Physical properties measured were:- IR (liquid film): Transparent between 4000 and 3100 cm -1 (no N-H); 1630 cm - 1 (C=0). MS: m/z = 326 (72.0%) (M + ); 311 (3.2%) (M + - CH 3 ); 215 (56.6%) (M + -CH 2 ==CH-NH.CO.cycl opropyl ); 1 H-nmr (D 2 θ): £ = 6.70 ppm. (2H m ) (H 5 and H 7 ); 6.30 ppm. (lH d ) (Hg) (J orth o =12 Hz); 3.76 ppm. (3H S ) (CH 3 0); 2.93 ppm. (3Hs) (N g -CH 3 ); 2.2-3.0 ppm. (3H m ) (N 10 ~CH 2 , CO-CH); 1.7-1.4 ppm. (lOHm) (methyl ene envelope); 0.98-0.6 ppm. (4H m ) (cycl opropyl dimethyl ene). Elemental analysis of the product gave the result:- Found:- C 73.7; H 8.2; N 8.55%. [C 2 oH26N 2 0 2 requires C 73.6; H 8.0; N 8.58%]. Preparation of ( L)-9-Methyl-10-Cyc] opropyl methyl -6-Methoxy- Ec iboline:- A solution of ( L)-9-methyl -10-cycl opropyl carboxy-6- methoxy- echibol ine (0.886 g) in tetrahydrofuran (100 ml) was boi ed under reflux with lithium a uminium hydride (0.62 g) for 4 hours. The excess of 1 ithium al uminium hydride was then decomposed by dropwise addition of a saturated aqueous solution of sodium sulphate and the suspended white solid was removed by filtration and washed with di-ethyl ether The organic phase was separated and the aqueous phase washed wel 1 with di-ethyl ether (three times, using 50 ml portions each time) The organic phases were combined and dried (using anhydrous magnesium sulphate) and the solvent removed by evaporation, to give a brown oil , (0.79 g, 93.2% yield). The material was crystal 1 ised from diethyl ether by cool ing the solution in a Dewar flask containing solid carbon dioxide and had me] ting point 33-34 degrees C. Physical properties measured were:- IR (KC1 disc) Transparent between 4000 and 3100 cm" 1 and between 1800 and 1610 cm -1 (no NH or =C0); MS: m/z = 312 (34.2%) (M + ); 297 (2.0%) (M + - CH 3 ); 215 (94.2%) (M + -CH 2 =CH.NH.CH 2 .cyc 1 opropyl ); 200 (13.6%) (215 - CH 3 ); 1 H-nmr (CDCl 3)7 £ = 6.60 ppm. (2H m ) (H5 and H 7 ); 6.15 ppm. (lH d ) (Hg) (J or tho = 12 Hz); 3.74 ppm. (3H S ) (OCH 3 ); 2.67 ppm. (3H S ) (Ng-CH 3 ) ; 3.5-2.2 ppm. (4H m ) (N 10 -CH 2 , N 10 -CH 2 ); 2.0-1.2 ppm. (10H m ) (methyl ene envelope); 1.0-0.3 ppm. (5H m ) (cycl opropyl ). Elemental analysis of the product gave the result:- Found:- C 76.7; H 9.2; N 8.9%. C C 20 H 28 N 2° re g uires c 76.9; H 9.0 ; N 8.95%]. The base was al so characterised as its picrate which was obtained from ethanol as yellow-orange needles, melting point 111-113 degrees C. Elemental analysis of the picrate gave the result:- Found:- C 57.8; H 5.8; N 12.7%. [C 26 H 31 N 2 0 requires C 57.7; H 5.8; N 12.9%]. The free base was 1 iberated from the picrate by treatment with sodium hydroxide solution, extraction with chloroform, passage of the chloroform solution through a short basic alumina column and removal of the solvent and had spectral data identical with those given above. EXAMPLE 4. Preparation of (- )-9-Methyl-10-Al lyl-6-Hydroxy-Echιbol ine:- A solution of boron tribromide (0.329 g) in dichl oro- methane (2.5 ml ) was dropwise, over a period of 30 minutes, to a stirred solution of (±.)-9-methyl -10-al 1 yl -6-methoxy- echibol ine (0.093 g) in dichl oro-methane (5 ml) cooled to 1 degree C. The mixture was al lowed to warm to ambient temperature over a period of 2 hours and then it was partially concentrated by sol vent evaporation. The mixture was then chilled using an ice bath (to 0 degrees C.) and methanol (1 ml) was added dropwise.- After stirring the cooled solution for 15 minutes, ethyl acetate was added to afford a pale yellow crystalline material (0.073 g, 52.5% yield) of the desired compound as its di-hydrobromide salt, melting point 184-186 degrees C. The compound was recrystal 1 ised from a mixture of methanol and ethyl acetate. Physical properties measured were:- MS: m/z = 284 (18.0%) (M + ), 214 (11.0%) 201 (30.0%) ^I-nmr (D 2 0): S * = 7.65 ppm. (lH d ) (Hg) (J 0 rtho = H Hz >■ ' 7.13 ppm. (lH d ) (H s ) (J me ta =4Hz); 7.05 ppm. (lH d ) (H 7 (J ortho =llHz, Jmeta 3141121 )* 5.7-5.2 ppm. (3H m ) (ethene protons); 3.94 ppm. (3H S ) (Ng-CH 3 ); 3.47 ppm. (2H d ) (N-CH 2 -CH=CH ) (J=7Hz); 3.25-1.2 ppm. (12H m ) (methylene envelope); Elemental analysis of the product gave the result:- - Foundr- C 45.5; H 6.05; N 6.2; Br 35.2%. [C 18 H 26 N 2 OBr 2 requires C 48.45; H 5.9; N 6.3; Br 35.8%] Preparation of intermediates for above :- Preparation of ( l ) -9-Methyl -10- l 1 yl -6-Methoxy-Echibol ine t - A sol ution of al lyl bromide (freshl y distil l ed) (0.094 g) in dichl oro-methane (1.25 ml ) and dimethyl formamide (0.5 ml ) was added, over a period of 2 hours, with stirring, to a sol ution of (±.)-9-methyl -6-methoxy-echibol ine (0.2 g) in d imethyl formamide ( 5 ml ) and water ( 0.2 ml ) to which anhydrous potassium carbonate (0.107 g) had been added. The mixture was then stirred at ambient temperature overnight and then water (50 ml ) was added. The mixture was then shaken with dichl oro-methane ( four times, using portions of 30 ml each time) . The combined dichl oro-methane extracts were then washed with water (four times, using portions of 30 ml each time) and saturated brine (four times, using portions of 30 ml each time), dried (using anhydrous magnesium sulphate), and the solvent was evaporated to give a brown oil (0.118 g, 51.6% yield). Physical properties measured were:- IR (1 iquid film): Transparent between 4000 and 3100 cm~l (no NH). MS: m/z = 298 (56.9%) (M + ); 283 (3.3%) (M + - CH 3 ); 200 (21.0%) (215-CH 3 ). 1 H-nmr (CDCl 3); 0 = 6.60 ppm. (2H m ) (H 5 and H 7 ); 6.20 ppm. (1H S ) (Hg) (J ortho = 12 Hz) ; 5.25-4.96 ppm. (3H m ) (ethene protons); 2.70 ppm. (3H S ) (Ng-CH 3 ); 3.6-2.3 ppm. (4H m ) (N 10 -CH 2 , N 10 CH 2 ) 2.06-1.0 ppm. (10H m ) (methyl ene envelope). Biological Testing: procedures and Results: The actions of 6-hydroxy-9, 10-dimethyl -echibol ine (alternatively named 1, 2, 3, 4-tetrahydro-6-hydroxy-9, 10- dimethyl -9a, 4a- (iminoethano) -9H-carbazol e) on the opioid receptors of the guinea pig ileum and mouse vas deferens were compared with those of its chemical anal ogue eserol ine and its pharmacological anal ogue morphine. Additional tests have also been made for analgesic and anti-chol inesterase activities. The actions of the two other echibol ine derivatives — 6-hydroxy-9-methy 1 -10-al 1 y 1 -echibol ine and 6-hydroxy-9-methy 1 - 10-cycl opropyl methyl -echibol ine — on peripheral opioid receptors are al so summarised. Transmurally stimulated guinea pig ileum. Sections of guinea-pig il eum were set up for transmural stimulation under a resting tension of 0.75g in Krebs solution bubbl ed with 5% carbon dioxide in oxygen at 37 degrees C according to the method of Kosterlitz and Watt (1968). Contractions were elicited from stainless steel electrodes, one of which was sited in the lumen at supramaximal voltage and a frequency of 0.05 Hz. Isometric contractions were recorded on a Rikadenki recorder, potential agonists were added directly to the bath and the contact time was until maximum inhibition had occurred. The responses of the preparation in the presence of na oxone were examined with the naloxone present in the physiological solution. Results were expressed as percent inhibition. In each experiment a log dose effect re ationship was determined using at least four concentrations in the absence of antagonist, and then in the presence of one or more concentrations of naloxone. Mouse vas deferens preparation. • Vasa deferentia were removed and mounted in 1.2 ml tissue baths under a resting tension of 200mg in Mg 2+ -free Krebs solution bubbled with a mixture of 95% oxygen and 5% carbon dioxide at 36 degrees C. The preparations were left for 1 hour to equil ibriate. Contractions were elicited from platinum electrodes fused to the sides of the tissue bath using supramaximal voltage (usually above 100 V), a pu se width of 1ms and a frequency of 0.1Hz. Isometric contractions were recorded on a Grass polygraph. As with the ileum, concentration effect re] ationships were determined in the absence then presence of naloxone. Compounds used for comparison of their effects were morphine sulphate, naloxone hydrochl oride, eserol ine and (+)- 6-hydroxy-9, 10-dimethyl -echibol ine hydrochl oride. Eserol ine was dissol ved in minimal 0.1N hydrochloric acid and dilutions made with water. Salts were dissol ved in water. Analgesic tests. Anal gesic activity was assessed using two methods in mice - the Hot plate Test and the Abdominal Constriction Test (acetic acid). The test drug was given by subcutaneous injection and the results expressed as ED50 with 95% confidence intervals. Antichol inesterase Test. Antichol inesterase activity was assessed using the method of Ellman, Courtney et al., (1961) using guinea pig ileum as the enzyme source. Guinea-pig ileum. In concentrations up to 200ng/ml , eserol ine caused a concentration-dependent inhibition of contractions induced by transmural stimul ation. This represented a maximum inhibition of about 50%. Increasing the concentration caused no further inhibition. This inhibitory action was antagonised by naloxone in a concentration-dependent manner (0.5, 5 and 50 ng/ml). in concentrations above 400ng/ml , and in the presence of naloxone, eserol ine enhanced electrical ly-induced contractions of the muscle. This is illustrated in Figure l. Log concentration-ef ect curves for morphine al one and in the presence 5 and 50 ng/ml naloxone are included in Figure 2. Morphine caused the famil iar inhibition of the preparation and naloxone antagonism was confirmed. ( -)-6-hydroxy-9, 10-dimethyl -echibol ine similarly inhibited the el ectrical ly- induced contractions of the guinea- pig ileum. It too was antagonised by naloxone in a concentration-dependent manner. In contrast to eserol ine, at no stage was an excitatory stage seen, and the maximum degree of inhibition of the preparation exceeded 50%, with some individual values showing over 90% inhibition. The potencies of morphine and ( L)-6-hydroxy-9, 10- dimethyl-echibol ine represented by their EC 50 va l ues are compared in Table 1. The EC^ Q values are calculated from bulked controls. Morphine was found to be 2.8 times more potent than (i)-6-hydroxy-9,10-dimethyl-echibol ine on this preparation. ■6-Hydroxy-9-methy l -10- al 1 yl - echibol ine inhibited contractions of the il eum with an IC 50 of 0.3 ug/ml , it being about ten times l ess potent than morphine. It was antagonised by nal oxone (5 and 50 ng/ml ) , and the characteristics of antagonism cl earl y indicated interaction with a different receptor popul ation than that with which morphine interacts. In concentrations up to 50 ng/ml 6-hydroxy-9-methyl -10- al ly -echibol ine had no antagonist activity against morphine in this preparation. 6-Hydroxy-9-methy 1 -10-cycl opropyl methyl -echibol ine al so inhibited the contractions of the il eum, but was of weaker potency with an IC 50 in excess of lug/ml . Nal oxone had l ittl e antagonist activity. The cycl o derivative had no detectabl e antagonist activity against morphine in this preparation. Mouse vas deferens . Concentration-effect 1 ines for morphine and ( L)-6- hydroxy-9, 10-dimethy] -echibol ine al one and in the presence of nal oxone are shown in Figure 3. EC 50 val ues for the two compounds are compared in Tabl e 2 , from which it can be seen that morphine was 3.6 times more potent than (i-)-δ-hydroxy- 9, 10-dimethyl -echibol ine on this preparation. Tabl e 2 gives an estimate of the degree of antagonism by nal oxone of the two opioid derivatives expressed as the l og dose ratios of the shifts in concentration-effect l ines. The values are derived from individual comparisons of the percentage inhibition of the preparations in the presence of a concentration of naloxone and that in the same preparation in the absence of naloxone. Whilst naloxone is clearly an antagonist of (l)-6- hydroxy-9, 10-dimethyl -echibol ine it is some ten times less effective as an antagonist than against morphine since the antagonism of morphine by 5 and 50 ng/ml naloxone quantitatively matches the antagonism of (i)-6-hydroxy-9,10- dimethyl -echibol ine by 50 and 500 ng/ml. .In contrast to eserol ine, 6-hydroxy-9, 10-dimethyl - echibol ine showed no evidence of chol inesterase inhibitory activity which otherwise characterises "chol inomimetic" analgesic compounds. When the potencies of morphine and 6-hydroxy-9, 10- dimethyl -echibol ine were compared on the two preparations in the absence then presence of the opioid antagonist naloxone, the results indicate that the receptor selectivity of 6- hydroxy-9, 10-dimethyl -echibol ine differs from that of morphine, and also this novel opioid structure differs clearly from other opioid "type" substances. This is indicative of a different spectrum of activity in vivo. These resul ts confirm that eserol ine has opiate activity and evidence for anti-cho] inesterase activity was al so seen. The enhancement of transmural contractions of the il um at high concentrations is characteristic of a chol inesterase inhibitor and is compatible with published data for anti¬ chol inesterase activity of eserol ine. The action of ( L)-6- hydroxy-9, 10-dimethyl -echibol ine on the ileum showed no evidence of chol inesterase inhibition. No enhancement of contractions was seen, and progressive opiate- like inhibition of the preparation progressed to close to 100%. The guinea-pig ileum and the mouse vas deferens contain different populations of the different types of opiate receptors and differences between potency ratios of agonists on the two. preparations have often been used to distinguish between different receptor sel ectivities (for example Paterson et al ., Br. Med. Bull., 39 (1983), pages 31-36). Additionall , naloxone is a more potent antagonist of opiate agonists at some types of receptors than others, and thus naloxone susceptibil ty has also been used to provide evidence of receptor interactions. These results also show that (- )-6-hydroxy-9, 10-dimethyl - echiboline possessed opiate-like activity on two well- documented "model s" of central activity and, on the above basis, that the receptor population which mediates the effects of (i)-6-hydroxy-9, 10-dimethyl -echibol ine differs from that of morphine . Analgesic activity predicted from the in vitro screen was confirmed using two standard animal tests. Naloxone was an effective antagonist, and the behaviour of the mice was suggestive of "morphine— 1 ike" activity. Substitution of the N-methyl substituent of an opioid compound with a bulky substituent (for example ally ) causes a change in pharmaco] ogical activity which may be a. a change from an agonist to an antagonist, -b. a change in the receptor selectivity of the agonist, c. a change to a drug which posseses both agonist and antagonist activities. 6-Hydroxy-9-methyl -10-al lyl -echibol ine possesses opioid agonist activity in vitro which is suggestive of analgesic activity in vivo. The relative lack of potency of naloxone as an antagonist is compatible with this agonist activity being mediated via a receptor different from that with which morphine acts. This receptor is likely to be the "kappa" receptor. Agonists at the kappa receptor common y have low dependence 1 iabil ity. Analgesic Testing in Mice. ED^Q and 95% confidence interval s. mg/kg, subcutaneous injection. 6-hy droxy-9 , 10- dimethy 1 morphine echibol ine Hot Pl ate 1.71 (1.34-2.18) 3.22 (2.88-3.62) Abdominal Constriction 0.23 (0.15-0.38) 0.41 (0.28-0.63) (Acetic acid) The drug was antagonised by naloxone. The potency relative to morphine is somewhat greater than that predicted from the in vitro tests. Anticholinesterase Test. Using guinea pig ileum as enzyme source, the echiboline derivative had no detectable anti-chol inesterase inhibitory activity in concentrations up to 6.4 ug/ml . TABLE 1 . EC 50 (± SD ) Guinea-pig Mouse vas ileum deferens (ng/ml ) ( g/m ) Compound A 12.1 0.283 (7.4 - 19.9) (0.143 - 0.559) Compound B 33.5 1.014 (23.8 -47.1) (0.728 - 1.413) Results show mean of not 1ess than 12 ' determinations with S.D. range. TABLE 2. Naloxone (ng/ml ) 5 10 500 Compound A Ileum 0.85 (+0.11) 1.91 (+0.10) Vas deferens 0.53 (+0.16) 1.50 (+0.23) Compound B Ileum 0.91 (+0.27) 1.54 (+0.22) Vas deferens 0.87 (+0.19) 1.66 (+0.13) The shifts in the 1og dose response curves on guinea-pig ileum and mouse vas deferens caused by naloxone, expressed as log dose ratios (±. S.D.). The results show mean of not less than 6 determinations. Compound A is morphine. Compound B is (i)-6-hydroxy-9,10-dimethyl-echiboline. KEY TO DETAILS SUMMARISED IN FIGURES 1 TO 3. FIGURE 1. The ef fects of esero l ine on e l ectrica l l y induce contractions of guinea pig il eum O al one , in the presence of nal oxone (0.5ng/ml ) , φ in the presence of nal oxone (5ng/ml ) , \ in the presence of nal oxone (50ng/ml ). Mean ± s.e.m. of between 6 and 20 determinations. FIGURE 2. The effects of morphine (A) and (±)-6-hydroxy-9,10-dimethyl- echiboline (B) on electrically induced contractions of the guinea pig ileum alone, Q in the presence of nal oxone (5ng/ml ), φ in the presence of nal oxone (50ng/ml ). Mean ±. s.e.m. of between 6 and 12 determinations. FIGURE 3. .The effects of morphine (A) and (i)-6-hydroxy-9,10-dimethyl- echiboline (B) on electrically induced contractions of the mouse vas deferens alone and in the presence of naloxone. The concentrations of naloxone were:- In Panel (A):- Q 5ng/ml and 50ng/πu , In Panel (B):- Q 50ng/ml and 500ng/ml . Mean ±. s.e.m. of between 6 and 12 determinations.

Claims: CLAIMS :- 1. New echiboline derivatives, useful as opiates, having the structure of a 6-hydroxy-9-methyl -echibol ine with a hydrocarbon substituent of up to 4 carbon atoms in the 10- position, and salts thereof. 2. New echiboline derivatives as claimed in Cl im 1, wherein the hydrocarbon substituent in the 10-position is of the structure R.CH 2 - wherein R represents a hydrogen atom or a hydrocarbon group of up to three carbons. 3. New organic compounds as claimed in Claim 2 wherein R is a cycl opropyl group or ethenyl group ' so " that the 10- substituent is correspon ingl a cycl opropyl -methyl or an al 1 y 1 group. . 6-Hydroxy-9 , 10-dimethyl -echibol in . 5. 6-Hydr oxy-9-methy 1 -10- al 1 yl -echibol ine . 6. 6-Hydroxy-9-methyl-10-cycl opropyl methyl -echibol ine . 7. Process for making a 6-hydroxy-9-methyl -echibol ine derivative as claimed in any one of claims 1 to 6, which comprises dealkylating a 6-al oxy-9-methyl -echibol ine having a hydrocarbon substituent of up to 4 carbon atoms in the 10-position and thereby converting the 6-al oxy group to a 6-hydroxy group. 8. Process as claimed in claim 7 wherein the deal kyl ation is carried out using boron tribromide as dealkylating reagent. 9. New echiboline derivatives, useful as intermediates for making the compounds claimed in Claims 1 to 6, namely 6- al oxy-9-methy 1 -echibol ine derivatives having a hydrocarbon substituent of up to 4 carbon atoms in the 10- position. 10. New echiboline derivatives as claimed in Claim 9 wherein the 6— al koxy group an al oxy group containing an alky] group of 1 to 4 carbon atoms, and preferably a methoxy group . 11. Process for making the compounds of Claims 9 or 10 which comprises reacting a 6-al koxy-9-methyl -echibol ine with a reagent which introduces the des ired hydrocarbon substituent into position 10. 12. Process as c l aimed in cl aim 11 wherein the reagent is of the structure R-CH 2 -Hal ogen, wherein R has the meaning stated in Claim 2. 13 . Process as cl aimed in cl aim 12 wherein the reagent is al l yl bromide. 14. Process for making the compounds of Cl aims 9 or 10 which comprises acyl ating a 6-al oxy-9-methyl -echibol ine to introduce the substituent R-CO- into the 10-position, and reducing the acyl group to RCH 2 ~ • 15. Process for making the compounds of Cl aims 9 or 10 in which the 10- substituent is a methyl group, which comprises formyl ating a 6-al koxy-echibol ine to produce the 9, 10-di- formyl -6-al koxy-echibol ine, and then reducing the formyl substituents to methyl groups. 16. Process as cl aimed in Cl aim 13 or 14 wherein the reducing agent is 1 ithium al uminium hydride. 17. Pharmaceutical compositions comprising a compound as cl aimed in any one of Cl aims 1 to 6 as active ingredient. 18. Use as an opioid of a compound as cl aimed in any one of cl aims 1 to 6 or a composition as cl aimed in Cl aim 17.

Inventors: COX BRIAN, REES JOHN MICHAEL HUGH, ROBINSON BRIAN, COX, BRIAN, REES, JOHN, MICHAEL, HUGH, ROBINSON, BRIAN
Applicants: UNIV MANCHESTER, THE VICTORIA UNIVERSITY OF MANCHESTER
Application year: 1987
Main classification: C07D487
IPC codes: C07D487