PROCESS FOR THE PREPARATION OF 1,3-DIAMINOPROPANE DERIVATIVES AND INTERMEDIATES USEFUL IN THIS PROCESS

Abstract: A process for the preparation of a compound of formula (B), or an addition salt and/or a solvate thereof, wherein Ra and Rd are independently phenyl optionally substituted by one, two or three of halogen, trifluoromethyl, C1-4 alkoxy, C1-4 alkyl, cyano, hydroxy, nitro, NReRf or O2SNReRf wherein Re and Rf are independently hydrogen or C1-6 alkyl or together are C3-6 polymethylene, or disubstituted at adjacent carbon atoms by C1-2 alkylenedioxy and optionally further substituted by one of the above groups; Rc is hydrogen or C1-4 alkyl; A represents C3 alkylene; and B represents C1-4 alkylene; which process comprises reacting a compound of the formula (VI): Ra-NH2, wherein Ra represents phenyl optionally substituted by one, two or three of halogen, trifluoromethyl, C1-4 alkoxy, C1-4 alkyl, cyano, hydroxy, nitro, NReRf or O2SNReRf wherein Re and Rf are independently hydrogen or C1-6 alkyl or together are C3-6 polymethylene, or disubstituted at adjacent carbon atoms by C1-2 alkylenedioxy and optionally further substituted by one of the above groups; with a compound of formula (VII), wherein Rd represents phenyl optionally substituted by one, two or three of halogen, trifluoromethyl, C1-4 alkoxy, C1-4 alkyl, cyano, hydroxy, nitro, NReRf or O2SNReRf wherein Re and Rf are independently hydrogen or C1-6 alkyl or together are C3-6 polymethylene, or disubstituted at adjacent carbon atoms by C1-2 alkylenedioxy and optionally further substituted by one of the above groups; Rc is hydrogen or C1-4 alkyl; and B represents C1-4 alkylene; and thereafter reducing the intermediate so formed and, optionally, forming an addition salt of the compound of formula (B) and/or a solvate thereof.

Description: PROCESS FOR THE PREPARATION OF 1 , 3-DIAMINOPROPANE DERIVATIVES AND INTERMEDIATES USEFUL IN THIS PROCESS This invention relates to a novel process, to certain novel compounds prepared by such process, to pharmaceutical compositions comprising such compounds and to the use of such compounds in medicine. European Patent Application, Publication Number 233762 discloses certain compounds of formula (A): R,- N - A- N - B -R d (A) wherein R a and R-j are independently phenyl optionally substituted by one, two or three of halogen, trifluoromethyl, C1-4 alkoxy, C1-4 alkyl, cyano, hydroxy, nitro, NR g Rf or O2SNReRf wherein Rg and Rf are independently hydrogen or C 1-5 alkyl or together are C3-6 polymethylene, or disubstituted at adjacent carbon atoms by C j -2 alkylenedioxy and optionally further substituted by one of the above groups; Rb is selected from (CH2) Z CN where z is 0 or an integer from 1 to 4 , C1-12 alkyl, C3-7 cycloalkyl, C3-7 cycloalkyl C1-4 alkyl, phenyl C1-4 alkyl, pyridyl, pyridyl Cl-4 alkyl, COR g , COCH 2 COR g , Sθ2R g , Cθ2R g , CONHRg and CSNHRg, where R g is selected from C3-12 alkyl, C3-7 cycloalkyl, C3-7 cycloalkyl C1-4 alkyl, phenyl and phenyl C1-4 alkyl, any alkyl moiety in R g optionally substituted by hydroxy or Cj-4 alkanoyloxy, any pyridyl or phenyl moiety in Kχ_ optionally substituted as defined for R a and R f j and any cycloalkyl moiety in R^ optionally substituted by one or two C1-4 alkyl groups; R ς is hydrogen or C 1-4 alkyl; A represents C2-5 alkylene; and B represents C1-4 alkylene; which compounds are stated to possess cardiovascular activity, in particular anti-angina activity. EP233762 also discloses intermediates for the preparation of the compound of formula (A) of formula (B): H I R a - N - A - N - B -R d (B) in which R a , R c , R-j, A, and B are as defined with respect to formula (A) or are groups convertible thereto. One particular compound from EP 233762 is the compound of Example 50 which is N-(3,4-dimemoxyphenyl)-N-[3-[[2-(3,4-dimethoxyphenyl)ethyl]methylamino]propyl]- 4-nitrobenzamide hydrochloride (hereinafter Compound I). EP233762 discloses a range of alternative methods of preparing the compound of formula (B). Synthetic Communications 2j , 3167-3180, (1990) discloses the preparation of β- aminoaldehydes. These compounds are stated to be unstable but they are demonstrated to react in situ with a range of different reagents to provide various aminated products. We have now found that in addition to the reagents disclosed in Synthetic Communications, a β-aminoaldehyde reacts with certain arylamines to provide arylimines which are readily reduced to a compound of formula (B) wherein variable A represents C3 alkylene. The reactions are high yielding and are readily carried out in the same reaction vessel providing a useful One pot' synthesis of the intermediate compounds (B) wherein variable A represents C3 alkylene and in particular the intermediate to Compound I. Accordingly, in its most preferred aspect the present invention provides a process for preparing a compound of formula (I) or an addition salt thereof and/or a solvate thereof: wherein R 1 , R 2 , R 4 and R 5 are each independently C1-.4 alkoxy and R^ is CI .5 alkyl, which process comprises reacting an arylamine of formula (II) : wherein R 4 and R^ are as defined in relation to formula (I) with a β-aminoaldehyde of formula (III): wherein R 1 , R 2 and R^ are as defined in relation to formula (I); and thereafter reducing the intermediate so formed and, optionally, forming an addition salt of the compound of formula (I) and/or a solvate thereof. Generally, the intermediate is an imine. The reaction is suitably carried out in an aprotie solvent, preferably tetrahydrofuran at any temperature providing a suitable rate of formation of the final product including temperatures up lo room temperature, but usually at a temperature below room temperature such as a temperature in the range of -15°C to 10°C, for example at 0°C. A compound of formula (III) may be prepared by the conjugate addition of acrolein to an amine of formula (IV): wherein R 1 , R 2 and R- are as defined in relation to the compounds of formula (I). The reaction is suitably carried out in an aprotie solvent, preferably tetrahydrofuran at any temperature providing a suitable rate of formulation of the final product including temperatures such as room temperature, but usually at a temperature below room temperature, such as a temperature in the range of -15°C to 5°C. Preferably, R 1 , R 2 , R 4 and R^ each independently represent methoxy. Preferably, R3 represents methyl. As indicated above, the reaction between the compounds of formulae (II) and (HI) proceeds via an intermediate, generally an imine, which is subsequently reduced to the compound of formula (I). In a further aspect, the invention provides a process for preparing a compound of the above defined formula (I),or an addition salt thereof and/or a solvate thereof which comprises reducing an intermediate compound prepared, and suitably isolated, from the reaction between a compound of formula (II) and a compound of formula (HI) and, optionally, forming an addition salt of the compound of formula (I) and/or a solvate thereof. In a particular aspect the present invention provides a process for preparing a compound of the above defined formula (I), or an addition salt thereof and/or a solvate thereof, which comprises reducing a compound of formula (V): wherein R 1 , R 2 , R 4 and R^ are each independently C1-.4 alkoxy and R^ is Cj.g alkyl and, optionally, forming an addition salt of the compound of formula (I) and/or a solvate thereof. The above mentioned reductions may be carried out using any suitable reducing procedure including catalytic hydrogenation, using catalysts such as palladium on carbon, for example 10% palladium on carbon , and metal hydride reduction, using such reagents as sodium borohydride. Catalytic hydrogenation is usually the prefened reduction method. The reaction conditions for the reduction are those conditions conventionally used for the particular reduction method chosen. For example when 10% palladium on carbon is used the reaction is carried out in tetrahydrofuran at below 30°C, usually at a elevated pressure, such as 40-50 psi, although the reaction will proceed at lower pressures such as atmosphere pressure. As indicated above the compound of formula (I) may be converted into an acid addition salt. A further aspect of the invention is a process for the preparation of an acid addition salt of a compound of the above defined formula (I), which process comprises treating the compound of formula (I) with an appropriate source of an acid. A preferred source of an acid is hydrogen chloride. The amount of acid used in the reaction can affect the quality of the final product For example when hydrogen chloride is used the amount of acid added is the stoichiometric amount required by the calculated yield of free base. In its most preferred aspect the present invention provides a process for preparing a compound of formula (I), or an acid addition salt thereof, which involves the following steps being carried out without isolating intermediate compounds (HI) and/or (V): (IV) + acrolein ► (III) (II) (I) < reduce M and optionally thereafter forming an acid addition salt of the compound of formula (I). Suitable reaction conditions are as described in relation to the reaction between the compounds of formulae (II) and (III). Preferably, the reaction between a compound of formula (IV) and acrolein is carried out in the presence of a catalytic amount of l,8-diazobicyclo[5.4.0]undec-7-ene (DBU). The compounds of formula (II) may be prepared according to known methods, for example by use of the methods disclosed in S.P. Findlay & G. Dougherty, J. Org. Chem. (1948) 13 560. The compounds of formula (IV) may be prepared according to known methods, for example by use of the methods disclosed in Paul Anand, J. Scient., Ind. Res India 12B (1958) 219, 223 As stated above the present process is suitable for the preparation of compounds of formula (B) wherein variable A represents C3 alkylene. Accordingly in a further aspect the present invention provides a process for the preparation of a compound of the above defined formula (B) in which variable A represents C3 alkylene, or an addition salt and/or a solvate thereof, which process comprises reacting a compound of formula (VI): R a -NH 2 (VI) wherein R a represents phenyl optionally substituted by one, two or three of halogen, trifluoromethyl, Ci -4 alkoxy, C1-4 alkyl, cyano, hydroxy, nitro, NR e Rf or O2SNR e Rf wherein R e and Rf are independently hydrogen or C\- alkyl or together are C3-6 polymethylene, or disubstituted at adjacent carbon atoms by Cj-2 alkylenedioxy and optionally further substituted by one of the above groups; with a compound of formula (VII): R 1 r c wherein, R_ represents phenyl optionally substituted by one, two or three of halogen, trifluoromethyl, C1-4 alkoxy, C1-4 alkyl, cyano, hydroxy, nitro, NR e Rf or O2SNR e Rf wherein R e and Rf are independently hydrogen or Cj-g alkyl or together are C3-6 polymethylene, or disubstituted at adjacent carbon atoms by Cj-2 alkylenedioxy and optionally further substituted by one of the above groups; R c is hydrogen or C 1-4 alkyl; and B represents Ci -4 alkylene; and thereafter reducing the intermediate so formed and, optionally, forming an addition salt of the compound of formula (B) and/or a solvate thereof. Generally , the intermediate is an imine. The reaction conditions for the reaction between the compounds of formulae (VI) and (VE) are analogous to those used in the reaction between the compounds of formulae (II) and (III). A compound of formula (VI) may be prepared in an analogous manner to that described for the compound of formula (II). A compound of formula (VII) may be prepared in an analogous manner to that described for the compound of formula (HI). The preferred forms of the reaction between the compounds of formulae (VI) and (VE) to give the compound of formula (B), are as described for the reactions between the compounds of formulae (II) and (III), including the isolation and reduction of an intermediate analogous to the imine of formula (V) discribed above. The compounds of formulae (III), (V) and (VII) also form part of the present invention, especially for use as intermediates. The following Example illustrates the invention but does not limit it in any way. Preparation of N-[2-(3,4-Dimethoxyphenyl)ethy]]-N-methyl-N , -(3,4- dimethoxyphenyl)-l,3-propanediamine, hydrochloride OCH, OCH, H 2 Pd/C Tetrahydrofuran (2.5L) was cooled to ca. 0° C under a nitrogen atmosphere and 90% acrolein (152ml) was added. A solution of 3,4-dimethoxy-N-methylphenethylamine (400g) and DBU (3.2ml) in tetrahydrofuran (IL) was then added slowly with stirring and cooling over 23 mins maintaining the temperature below 5°C. A further amount of tetrahydrofuran (250ml) was used to wash in any remaining solution in the addition funnel. The reaction mixture was stined for 30mins at ca. 0°C then added to 3,4-dimethoxyaniline (315g) and 10% palladium on carbon (40g). The mixture was then hydrogenated at ambient temperature, 40-50 psi. pressure for ca 20 hours. The catalyst was removed by filtration and the filtrate treated with 4.74 molar hydrogen chloride in ethanol (303ml). The solution was stined for 1 hour then cooled at ca. 0° C for ca. 1.5 hours. The resulting suspension was filtered, washed with tetrahydrofuran and air dried to give N-[2-(3,4-Dimethoxyphenyl)ethyl]-N-methyl- N'-(3,4-dimethoxyphenyl)-l,3-propanediamine hydrochloride as an off white solid, 557g. A sample of the crude product (180g) was recrystallised from ethanol (1050ml) to give the product as an off white solid, 170g (60% overall yield). δ(DMSO) : 1.95-2.02 (m, 2H); 2.77 (s, 3H); 2.97-3.01 (m, 2H); 3.07 (t, J = 6.5 Hz, 2H); 3.17-3.25 (m, 4H); 3.36 (bs, IH) 3.62 (s, 3H); 3.70 (s, 3H); 3.72 (s, 3H); 3.75 (s, 3H); 6.08 (dd, J = 2.5, 8.5 Hz, IH); 6.31 (d, J = 2.5 Hz, IH); 6.72 (d, J = 8.5 Hz, IH); 6.77 (dd, J = 1.8, 8.2 Hz, IH); 6.87-6.91 (m, 2H)

Claims: Claims 1. A process for the preparation of a compound of a compound of formula (B): \ R a - N - A - N - B -R d (β) or an addition salt and/or a solvate thereof, wherein R a and R^ are independently phenyl optionally substituted by one, two or three of halogen, trifluoromethyl, C1-4 alkoxy, C1-4 alkyl, cyano, hydroxy, nitro, NR e Rf or O2SNR e Rf wherein R e and Rf are independently hydrogen or C - alkyl or together are C3-6 polymethylene, or disubstituted at adjacent carbon atoms by Cj-2 alkylenedioxy and optionally further substituted by one of the above groups; R D is selected from (CH2) Z CN where z is 0 or an integer from 1 to 4 , Cj-12 alkyl, C3-7 cycloalkyl, C3-7 cycloalkyl C1-4 alkyl, phenyl C1-4 alkyl, pyridyl, pyridyl C1-4 alkyl, COR g , COCH 2 CORg, SO 2 Rg, CO2R g , CONHRg and CSNHRg, where Rg is selected from C3-12 alkyl, C3-7 cycloalkyl, C3-7 cycloalkyl C1-4 alkyl, phenyl and phenyl C1-4 alkyl, any alkyl moiety in R g optionally substituted by hydroxy or C1-4 alkanoyloxy, any pyridyl or phenyl moiety in R D optionally substituted as defined for R a and R_ and any cycloalkyl moiety in R optionally substituted by one or two C1-4 alkyl groups; R Q is hydrogen or C 1-4 alkyl; A represents C3 alkylene; and B represents C1-4 alkylene; which process comprises reacting a compound of formula (VI): R a -NH 2 (VI) wherein R a represents phenyl optionally substituted by one, two or three of halogen, trifluoromethyl, C1-4 alkoxy, C1-4 alkyl, cyano, hydroxy, nitro, NR e Rf or O2SNR e Rf wherein R e and Rf are independently hydrogen or C\-^ alkyl or together are C3-6 polymethylene, or disubstituted at adjacent carbon atoms by Cj-2 alkylenedioxy and optionally further substituted by one of the above groups; with a compound of formula (VII): R„ R„ -B-N. H (VII) wherein, R_ represents phenyl optionally substituted by one, two or three of halogen, trifluoromethyl, C1-4 alkoxy, C1-4 alkyl, cyano, hydroxy, nitro, NRgRf or O2SNR Rf wherein R e and Rf are independently hydrogen or C - alkyl or together are C3-6 polymethylene, or disubstituted at adjacent carbon atoms by Cj-2 alkylenedioxy and optionally further substituted by one of the above groups; Rc is hydrogen or C 1-4 alkyl; and B represents C1-4 alkylene ); and thereafter reducing the intermediate so formed and, optionally, forming an addition salt of the compound of formula (B) and or a solvate thereof. 2. A process for preparing a compound of formula (I) or an addition salt thereof and/or a solvate thereof: wherein R , R 2 , R4 and R^ are each independently C1.4 alkoxy and R^ is C . alkyl, which process comprises reacting an arylamine of formula (II): wherein R 4 and R^ are as defined in relation to formula (I) with a β-aminoaldehyde of formula (III): wherein R , R 2 and R^ are as defined in relation to formula (I); and thereafter reducing the intermediate so formed and, optionally, forming an addition salt of the compound of formula (I) and/or a solvate thereof. 3. A process according to claim 2, wherein the intermediate is an imine of formula (V): wherein R*, R 2 , R 4 and R^ are each independently C1.4 alkoxy and R^ is C\. alkyl. 4. A process according to claim 2, wherein R , R 2 , R 4 and R^ each independently represent methoxy. 5. A process according to claim 2,wherein R^ represents methyl. 6. A process for preparing a compound of formula (I), or an acid addition salt thereof, which involves the following steps being carried out without isolating intermediate compounds (III) and/or (V): (IV) + acrolein ► (III) with (II) (I) reduce (V) and optionally thereafter forming an acid addition salt of the compound of formula (I). A process according to claim 2, for the preparation of N-[2-(3,4- Dimethoxyphenyl)ethyl]-N-methyl-N'-(3,4-dimethoxyphenyl)-l,3- propanediamine, hydrochloride. 8. A compound: (a) of formula (IH) as defined in claim 2; (b) of formula (V) as defined in claim 3; or (c) of formula (VII) as defined in claim 1.

Inventors: ATTRILL ROBIN PATRICK, RAMSAY THOMAS WEIR, ATTRILL, ROBIN, PATRICK, RAMSAY, THOMAS, WEIR
Applicants: ATTRILL ROBIN PATRICK, RAMSAY THOMAS WEIR, SMITHKLINE BEECHAM PLC, ATTRILL, ROBIN, PATRICK, RAMSAY, THOMAS, WEIR
Application year: 1996
Main classification: C07C209
IPC codes: C07C213, C07C217, C07C251