The invention provides new silyl derivatives of 5,6,7,8-tetrahydroquinolines and related compounds. The tetrahydroquinolines are substiuted at the 8-position by the group SiR.sub.3 where R may be one of various hydrocarbon groups or an electron donating substituent. The 8-position may also carry a lithium, sodium or potassium atom. The new silyl derivatives may be prepared by treating a corresponding 8-lithio, sodio or potassio tetrahydroquinoline with a silyl halide R.sub.3 SiHal followed by a metal compound R*M where M is sodium, potassium or lithium and R* is alkyl, cycloalkyl, aralkyl or aryl or an amine residue. The new silyl derivatives are useful intermediates for the preparation of known 5,6,7,8-tetrahydroquinline-8-nitriles, amides and thioamides employing an alkyl silyl isothiocyanate or cyanate. The nitriles and thioamides are anti-ulcer agents. The related compounds may be made by analogous methods.

The invention relates to novel silyl derivatives of fused carbocyclic ring 
derivatives of pyridine processes using the novel derivatives. 
In our United Kingdom Patent Specification No. 1463666 we described a 
process for preparing tetrahydroquinoline-8-thiocarboxamides, nitriles and 
carboxamides and related compounds by treating a corresponding sodio, 
lithio, potassio or magnesium halide derivative with a silyl compound of 
formula R.sub.x Si(NCY).sub.4-x wherein R is alkyl, aryl or aralkyl, Y is 
oxygen or sulphur and x has a value from 0 to 3 and subjecting the product 
to hydrolysis or alcoholysis. The reaction is conducted under anhydrous 
conditions preferably in an inert solvent, for example, a hydrocarbon 
solvent such as benzene, toluene or n-hexane. This is a very short route 
for preparing tetrahydroquinoline-8-thiocarboxamides directly from the 
above mentioned metal derivatives of the corresponding 
tetrahydroquinolines. However we have found that the overall yields are 
usually lower than 50%. After extensive research and investigation of this 
reaction we have discovered that better yields can usually be obtained by 
using a novel silyl derivative of the tetrahydroquinoline or related 
compound and novel metallated derivatives thereof. 
Accordingly, this invention provides in one aspect, new silyl compounds of 
formula I. 
##STR1## 
wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are the same or 
different and represent hydrogen or alkyl, cycloalkyl, aralkyl, or aryl 
radicals, any of which radicals may be substituted, or R.sup.1 and R.sup.2 
taken together, or R.sup.2 and R.sup.3 taken together, form a 5, 6, or 7 
membered ring which may be saturated or unsaturated and substituted or 
unsubstituted, and when R.sup.1 and R.sup.2 form a ring, the ring has the 
same number of carbon atoms as the ring carrying R.sup.4, R.sup.4 and 
R.sup.5 may also represent alkoxy, n is 1, 2 or 3 and X is hydrogen or 
lithium, sodium or potassium and R is alkyl, cycloalkyl, aralkyl or aryl 
or R is selected from electron donating substituents including alkoxy, 
cycloalkoxy, aralkoxy, aryloxy, alkylthio, cycloalkylthio, aralkylthio, or 
arylthio or the group R.sup.b R.sup.c N- wherein R.sup.b and R.sup.c are 
selected from alkyl, cycloalkyl, aryl and aralkyl or R.sup.b and R.sup.c 
may be joined to form a heterocyclic ring with the nitrogen atom (e.g., a 
piperidinyl Kor pyrrolidinyl ring, which may be substituted e.g., by 
alkyl). 
The groups R are not necessarily all the same but it is preferred that 
Si(R).sub.3 is tri-loweralkyl silyl or more preferably trimethyl silyl. 
When any of R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 or R is an alkyl 
radical it is preferred that this is a lower alkyl radical of 1 to 6 
carbon atoms which may have a straight or branched chain e.g., methyl, 
ethyl, n- and iso-propyl and n-, s- and t- butyl. When R, R.sup.4 or 
R.sup.5 is an alkoxy radical it is preferred that the radical is lower 
alkoxy in which the alkyl portion has 1 to 6 carbon atoms and is as 
defined above, for an alkyl radical. 
When any of R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 or R is a 
cycloalkyl radical such radicals having from 4 to 6 carbon atoms are 
preferred i.e. cyclobutyl, cyclopentyl or cyclohexyl. 
An aralkyl group may be an arylalkyl group in which the alkyl portion is as 
described herein for an alkyl group. Preferred aralkyl groups are those 
having from 7-12 carbon atoms. 
When any of R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 or R is an aryl 
group it is preferably phenyl or substituted phenyl (substituted by e.g., 
alkyl, alkoxy, or trifluoromethyl. 
Preferably the compound of formula I is a tetrahydroquinoline derivative 
i.e. n is 2. 
The compounds of formula I may be prepared by treating a compound of 
formula II 
##STR2## 
wherein M is sodium, potassium or lithium, and R.sup.1, R.sup.2, R.sup.3, 
R.sup.4, R.sup.5 and n are as defined in connection with formula I with a 
silylating agent of formula (R).sub.3 SiHal where R is as defined 
previously and Hal is chlorine, bromine or iodine to obtain a compound I, 
wherein X is hydrogen, and if desired treating this with a metal compound 
R*M where M is sodium, potassium or lithium and R* is alkyl, cycloalkyl, 
aralkyl or aryl or an amine residue, to obtain a compound of formula I 
wherein X is sodium potassium or lithium. 
The above reactions may be carried out in any suitable reaction medium 
solvent. Thus the first stage is conveniently carried out in a reaction 
medium comprising an ether solvent, preferably tetrahydrofuran but other 
cyclic ethers e.g., dioxan, may be used or dialkyl ethers, wherein the 
alkyl group has from 1 to 6 carbon atoms e.g., diethyl ether. Other 
reaction media which may be used are hydrocarbon solvents such as benzene, 
toluene or n-hexane. The reaction medium may comprise two or more of the 
above solvents. 
Conveniently the starting material of formula II may be prepared in situ by 
reaction of a compound of formula II, wherein M is hydrogen with a 
suitable organometallic compound such as an alkyl, aryl or aralkyl 
lithium, sodium or potassium compound as described in UK Patent 
Specification No. 1432378 or using the modification described in UK Patent 
Specification No. 1463666, wherein a metal amide is reacted with a 
compound of formula II wherein M is hydrogen. The metal amide may be 
formed in situ and may be any of those described in UK Patent 
Specification No. 1463666 viz. an amide derived from a secondary amine 
such as a dialkylamine e.g. diethylamine, di-isopropylamine, ditertiary 
butylamine, di-n-decylamine, dicyclohexylamine, N-t-amyl-N-t-butyl-amine, 
N-isopropyl-N-cyclohexylamine, or 
N-(1-ethylcyclohexyl)-1,1,3,3-tetramethylbutylamine or a cyclic compound 
e.g. piperidine, or 2,2,6,6-tetramethylpiperidine. Alternatively any of 
the metal amides described in co-pending U.S. Ser. No. 472787 filed Mar. 
7, 1983 may be used. These metal amides have the formula III 
##STR3## 
wherein R.sup.14 is a straight or branched chain alkyl group of 1 to 6 
carbon atoms or an aryl group, R.sup.11 is hydrogen, aryl or a tertiary 
alkyl group of 4-6 carbon atoms, R.sup.12 is aryl or a tertiary alkyl 
group of 4-6 carbon atoms, R.sup.13 is a branched chain alkyl of 3 to 6 
carbon atoms; X.sup.1 is lithium, sodium or potassium. These metal amides 
are conveniently prepared by a novel process described in U.S. Ser. No. 
472787, namely reacting a compound of formula IV. 
##STR4## 
wherein R.sup.11, R.sup.12 and R.sup.13 are as defined above with a metal 
alkyl MR.sup.14 where R.sup.14 is as defined above and M is lithium, 
sodium or potassium, in an inert non-polar solvent to obtain a compound of 
formula III. 
Since the starting compound of formula II is conveniently prepared in situ 
using the metal alkyl in a hydrocarbon solvent and the silylation reaction 
is conveniently carried out in an ether, the reaction medium will often 
comprise a hydrocarbon/ether solvent. Furthermore when a compound of 
formula I wherein X is sodium, potassium or lithium is desired the 
reaction with the metal compound R*M may be carried out by adding the 
metal compound in a hydrocarbon solvent, e.g., n-hexane, to a solution of 
compound I where X is hydrogen, prepared in situ. As will be apparent a 
metal amide, such as one discussed above, may be used as the compound R*M 
in the preparation of a compound of formula I where X is sodium, potassium 
or lithium. However, there will not normally be any advantage in using a 
metal amide and it is preferable to use a metal alkyl, aryl or aralkyl in 
both the preparation of the starting compound of formula II and the end 
product of formula I where X is sodium, potassium or lithium. 
The new chemical intermediates of formula I may be used in various chemical 
processes which are all included in the invention. 
Accordingly this invention provides in one aspect, a process for preparing 
compounds of formula V 
##STR5## 
or acid addition salts thereof, wherein R.sup.1, R.sup.2 R.sup.3, R.sup.4, 
R.sup.5 and n are as defined in connection with formula I and Z is CN, 
CONH.sub.2 or CSNH.sub.2 which process comprises treating a compound of 
formula I as defined above, wherein X is sodium, potassium or lithium with 
a silyl compound of formula VI R.sub.x.sup.a Si(NCY).sub.4-x wherein 
R.sup.a is selected from electron donating substituents, [including 
alkoxy, cycloalkoxy, aralkoxy, aryloxy, alkylthio, cycloalkylthio, 
aralkylthio, arylthio] or the group R.sup.b R.sup.c N-wherein R.sup.b and 
R.sup.c are selected from alkyl, cycloalkyl, aryl and aralkyl or R.sup.b 
and R.sup.c may be joined to form a heterocyclic ring with the nitrogen 
atom (e.g., a piperidinyl or pyrrolidinyl ring, which may be substituted 
e.g., by alkyl), and hydrocarbon substituents selected from alkyl, 
cycloalkyl, aralkyl or aryl, Y is oxygen or sulphur, x has a value from 
0-3, then subjecting the product to hydrolysis or alcoholysis with the 
proviso that when a compound of formula V in which Z is CN is desired the 
molar ratio of compound R.sub.x.sup.a Si(NCY).sub.4-x to compound I is at 
least 2:1 and x is 3 and Y is S and if desired isolating the product as an 
acid addition salt. 
The compounds of formula V are known compounds which are described in UK 
Patent Specification Nos. 1463666, 1432378, 1463668, 1465651 and 1495993. 
The compounds of formula V in which Z is CSNH.sub.2 are anti-ulcer agents 
which display anti-ulcer and/or anti-secretory activity in standard test 
procedures. The nitriles of formula V where Z is CN are intermediates for 
the corresponding thioamides and usually also display anti-ulcer and/or 
anti-secretory activity. The amides of formula V in which Z is CONH.sub.2 
are intermediates for the corresponding nitriles and thioamides. 
The preferred reaction medium for the above process is an ether solvent 
e.g., a dialkyl ether, wherein the alkyl group has from 1 to 6 carbon 
atoms, e.g., diethyl ether, or a cyclic ether such as tetrahydrofuran or 
dioxan. Other reaction media which may be used are hydrocarbon solvents 
such as benzene, toluene or n-hexane. Mixtures of two or more of the above 
mentioned solvents may be used. 
In a preferred aspect of this process a compound R.sub.3.sup.a SiNCY is 
used in which one group R.sup.a is an electron donating substituent or a 
branched chain alkyl (e.g. C.sub.3 -C.sub.10), branched aralkyl, 
cycloalkyl (e.g. C.sub.4 -C.sub.8), or aryl and the other two groups 
R.sup.a are alkyl, e.g., t-butyldimethylsilyl isothiocyanate. 
When R.sup.a, R.sup.b or R.sup.c is an alkyl radical, an aryl radical, an 
aralkyl radical or a cycloalkyl radical the radical may be as defined for 
R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5. When R.sup.a is an alkoxy 
radical, the radical may be C.sub.1 -C.sub.10 but is preferably as defined 
for R.sup.4 and R.sup.5. When R or R.sup.a is an alkylthio group the alkyl 
portion is as defined for an alkyl group and R.sup.a may be C.sub.1 
-C.sub.10. If R or R.sup.a is cycloalkoxy or cycloalkylthio the cycloalkyl 
portion of this group may be as described for a cycloalkyl group and 
R.sup.a may be C.sub.4 to C.sub.8. 
An aralkyloxy or aralkylthio group may be such a group in which the aralkyl 
portion is as described for an aralkyl group. The aryl portion is 
preferably phenyl. An aryloxy or arylthio group may be such a group in 
which the aryl portion is as defined for an aryl group, 2,6-disubstituted 
phenyl being a preferred aryl portion. 
When it is desired to prepare nitriles of formula V by the above reaction 
instead of using 2 or more moles of compound R.sub.x.sup.a Si(NCY).sub.4-x 
to complete I the reaction may be carried out by reacting 1 mol of 
compound R.sub.x.sup.a Si(NCY).sub.4-x with compound I wherein X is Na, K 
or Li followed by addition of 1 or more mols of R.sub.x.sup.a 
SiHal.sub.4-x wherein R.sup.a and x are as defined previously and Hal is 
chlorine or bromine, R.sup.a and x in this compound need not be the same 
as in the reagent R.sub.x.sup.a Si(NCY).sub.4-x. This process for 
preparing nitriles is also included in the invention. 
The new chemical intermediates of formula I may also be used in a variety 
of reactions in addition to those already discussed. Examples of reactions 
are given below: 
(1) To prepare substituted thioamides corresponding to those of formula V 
where Z is CSNHR.sup.d and R.sup.d is alkyl instead of Z is CSNH.sub.2. 
These substituted thioamides may be obtained by treating a compound of 
formula I, wherein X is Na, K or Li with a compound of formula R.sup.d NCS 
followed by treating the product with hydrogen ions. The source of 
hydrogen ions may be water, an alcohol e.g., a lower alkanol of 1-6 carbon 
atoms or an aqueous mineral acid e.g., a hydrohalic acid, preferably 
hydrochloric acid, or an organic acid such as acetic acid. 
(2) To prepare substituted amides corresponding to those of formula V where 
Z is CONHR.sup.d and R.sup.d is alkyl, instead of X is CONH.sub.2. These 
substituted amides may be obtained by treating a compound of formula I 
wherein X is Na, K or Li with a compound of formula R.sup.d NCO, e.g. 
methyl isocyanate followed by treating the product with hydrogen ions as 
discussed in paragraph (1) above. 
(3) To prepare carboxylic acids, their salts and esters of formula V 
wherein Z is CO.sub.2 H,CO.sub.2 M where M is sodium potassium or lithium 
or CO.sub.2 R.sup.e and R.sup.e is alkyl, aralkyl or aryl. The esters may 
be prepared by treating a compound of formula I wherein X is Na, K or Li 
with a haloformate HalCO.sub.2 R.sup.e where Hal is chlorine, bromine or 
iodine and R.sup.e is as defined previously followed by treating the 
product with hydrogen ions e.g. as discussed in paragraph (1) above. The 
carboxylic acid salts may be obtained by treating a compound of formula I 
wherein X is Na, K or Li with carbon dioxide. These salts may be converted 
to the free acid by treatment with acid e.g., mineral acids, e.g., of the 
type discussed in (1) above. 
The three processes described above are all included in the invention. 
One advantage of the new silyl compounds of formula I when used to prepare 
compounds of formula V is that there is a reduction in the tendency for 
side reactions to occur. For example, in the process of UK Patent 
Specification No. 1463666 it has been found that with certain alkyl 
substituted tetrahydroquinolines (e.g., 4-methyl compounds) the yields of 
final product are less than expected. This is due, at least in part, to 
the tetrahydro-8-lithio-4-methylquinoline being converted to a 
4-lithiomethyl-tetrahydroquinoline. It has been found that the novel 
tetrahydro-8-lithio-4-methyl-8-silyl-quinoline does not undergo a similar 
reaction so that the 4-methyl group is not lithiated.

THE FOLLOWING EXAMPLES ILLUSTRATE THE INVENTION 
Example 1 
5,6,7,8-Tetrahydro-8-trimethylsilyl-3-methylquinoline 
A mixture of 5,6,7,8-tetrahydro-3-methylquinoline (29.4 g, 0.2 M) and 
tetrahydrofuran (THF) (50 ml) was added to a mixture of a 1.55 molar 
solution of butyl lithium in hexane (129 ml, 0.2 M) and THF (50 ml), 
maintained below 10.degree.. After 0.5 hour the mixture was blown over by 
inert gas onto a mixture of trimethylsilyl chloride (50 ml, 0.4 M) in the 
THF (100 ml), maintained below 10.degree.. After 0.5 hour, the mixture was 
evaporated and the residue extracted with hexane. The hexane extracts were 
evaporated with the residue distilled to give the title compound (40 g, 
91%) b.p. 118.degree.-124.degree./5 mbar. (Found: C70.9; H,9.65; N,6.4% 
C.sub.13 H.sub.21 NSi requires: C,71.2; H,9.6; N6.4%). 
Example 2 
5,6,7,8-Tetrahydro-8-trimethylsilyl-4-methylquinoline 
The title compound was prepared in a similar manner to that described in 
Example 1 using 5,6,7,8-tetrahydro-4-methylquinoline (0.1 M), butyl 
lithium (0.11 M) and trimethylsilyl chloride (0.2 M) in 95% yield b.p. 
80.degree./0.1 mm (Found: C71.1; H,9.3; N,6.0 C.sub.13 N.sub.21 NSi 
requires: C71.2; H,9.6; N,6.4%). 
Example 3 
5,6,7,8-Tetrahydro-3-methylquinoline-8-thiocarboxamide 
A mixture of a 1.55 molar solution of butyl lithium in hexane (6.45 ml, 1O 
mM) and THF (10 ml) maintained below 10.degree. was treated with a 
solution of 5,6,7,8-tetrahydro-8-trimethylsilyl-3-methylquinoline (2.2 g, 
10 mM) in THF (1O ml) to obtain 5,6,7,8-tetrahydro- 
-8-lithio-8-trimethylsilyl-3-methylquinoline. After 0.5 hour a 22% 
solution of t-butyldimethylsilyl isothiocyanate in benzene (6.9 g, 1O mM) 
was added dropwise. After 0.5 hour the reaction mixture was quenched with 
2N hydrochloric acid (25 ml) and after 1 hour the aqueous layer was 
separated, basified (to pH9) and extracted with dichloromethane 
(2.times.50 ml). The organic extracts were dried and evaporated to give 
the title thioamide (2.1 g, c 100%). Recrystallisation from benzene gave 
analytically pure material (1.9 g, 88%) m.p. 153.degree., identical to 
authentic material (Found: C63.7; H,6.9; N,13.4% C.sub.11 H.sub.14 N.sub.2 
S requires: C64.0; H,6.8; N,13.6%). 
Example 4 
5,6,7,8-Tetrahydro-4-methylquinoline-8-thiocarboxamide 
A mixture of a 1.55 molar solution of n-butyl lithium in hexane (14.2 ml, 
22mM) and THF (25 ml), maintained below 5.degree. was treated with a 
solution of 5,6,7,8-tetrahydro-8-trimethylsilyl- 4-methylquinoline (4.4 g, 
20 mM) in THF (10 ml) to give 5,6,7,8-tetrahydro-8-lithio-8-trimethylsilyl 
-4-methylquinoline. After 0.5 hour a solution of t-butyldimethylsilyl 
isothiocyanate (22 mM) in benzene (15 ml) was added; after a further 0.5 
hour the mixture was quenched with 0.5 N hydrochloric acid (60 ml). After 
1 hour toluene (50 ml) was added, the aqueous layer was separated, 
adjusted to pH10 and extracted with dichloromethane. The organic extract 
was evaporated and chromatographed on silica using ether as eluant. The 
title thioamide was obtained in 60% yield (identical to authentic 
material) together with the corresponding nitrile (20%) and 
5,6,7,8-tetrahydro-4-methylquinoline (20%). 
Example 5 
5,6,7,8-Tetrahydro-4-methylquinoline-8-(N-methylthiocarboxamide 
A mixture of a 1.55 molar solution of n-butyl lithium in hexane (12.9 ml, 
20 mM) and THF (10 ml), maintained at 5.degree. was treated with a 
solution of 5,6,7,8-tetrahydro-8-trimethylsilyl-4-methylquinoline (4.34 g, 
20 mM) to obtain 
5,6,7,8-tetrahydro-8-lithio-8-trimethylsilyl-4-methyl-quinoline. After 0.5 
hour a solution of methyl isothiocyanate (1.46 g, 20 mM) in THF (10 ml) 
was added and after a further 0.5 hour the mixture was quenched with N 
hydrochloric acid (50 ml). Ether was added and the aqueous layer was 
separated, adjusted to pH10 and extracted with dichloromethane(2.times.50 
ml). The organic extract was dried, evaporated, dissolved in ethyl acetate 
and passed through a short pad of silica. Evaporation of the eluate 
followed by recrystallisation from ethyl acetate gate the title compound 
(2.4 g) m.p. 151.degree.-3.degree.. The hydrochloride (from propan-2-ol) 
had m.p. 240.degree.-5.degree.(d) (Found: C,56.5; H,6.6; N,10.6% C.sub.12 
H.sub.16 N.sub.2 SHCl requires C,56.1; H,6.7; N,10.9%). 
Example 6 
8-Cyano-5,6,7,8-tetrahydro-3-methylquinoline 
A mixture of a solution of 1.5 molar n-butyl lithium in hexane (12.9 ml, 20 
mM) and THF (10 ml), maintained at 5.degree. was treated with a solution 
of 5,6,7,8-tetrahydro-8-trimethylsilyl-3-methylquinoline (4.34 g 20 mM) to 
obtain 5,6,7,8-tetrahydro-8-lithio-8- trimethylsilyl-3-methylquinoline. 
After 0.5 hour a solution of t-butyldimethylsilyl isothiocyanate (7.0 g 40 
mM) was added and the mixture allowed to warm to 20.degree. over 12 hours. 
The reaction was quenched with 2N hydrochloric acid and stirred 1 hour. 
The mixture was extracted with ether, the aqueous phase adjusted to pHlO 
and extracted with ether. The organic extracts were dried and evaporated 
to give the title compound (3 g, 85%) identical with authentic material. 
Example 7 
5,6,7,8-Tetrahydro-8-dimethoxymethylsilyl-3-methylquinoline 
The title compound was prepared in a similar manner to that described in 
Example 1 using 5,6,7,8-tetrahydro-3-methylquinoline (0.01 M), butyl 
lithium (0.01 M) and dimethoxymethylsilyl chloride (0.015 M). The sample 
was distilled twice using a kugelrohr apparatus to give the title compound 
(0.25 g) bp 110.degree.-120.degree. C./0.5 mm. 
Example 8 
5,6,7,8-Tetrahydro-3-methylquinoline-8-(N-methyl) carboxamide 
8-Lithio-5,6,7,8-tetrahydro-3-methyl-8-trimethylsilylquinoline, prepared as 
in Example 3, is treated at -20.degree. C. under nitrogen with a solution 
of 1 equivalent of methyl isocyanate in tetrahydrofuran. After this 
addition the mixture is allowed to warm to ambient temperature and the 
solvent removed by evaporation. The residue is dissolved in 2NHCl and 
washed with ether, basified with Na.sub.2 CO.sub.3 and extracted with 
chloroform. The extracts are dried and evaporated and the residue purified 
by chromatography to give the title compound. 
Example 9 
Methyl-5,6,7,8-tetrahydro-3-methylquinoline-8-carboxylate 
8-Lithio-5,6,7,8-tetrahydro-3-methyl-8-trimethylsilylquinoline, prepared as 
in Example 3, is treated with 1 equivalent of methyl chloroformate in THF 
at -20.degree. C. under nitrogen. After the addition the mixture is 
allowed to warm to ambient temperature and the solvent removed by 
evaporation. The residue is dissolved in 2NHCl and washed with ether 
basified with Na.sub.2 CO.sub.3 and extracted with chloroform. The 
extracts are dried and evaporated. Distillation of the residue gives the 
title compound as a pale yellow oil bp 120.degree./0.25 mm. 
Example 10 
Methyl-5,6,7,8-tetrahydro-3-methylquinoline-8-carboxylate 
8-Lithio-5,6,7,8-tetrahydro-3-methyl-8-trimethylsilylquinoline, prepared as 
in Example 3, is blown over onto ether at 0.degree. C. through which a 
vigorous stream of CO.sub.2 gas is being passed. After the addition the 
resulting solid, lithium 
5,6,7,8-tetrahydro-3-methyl-8-trimethylsilylquinoline-8-carboxylate, is 
removed by filtration. This is then dissolved in methanol (200 ml) and the 
solution treated with HCl gas to excess and heated at reflux for 4 hours. 
The solvent is removed in vacuo and the residue dissolved in water (50 
ml), made alkaline with 2N NaOH and extracted with chloroform. The 
extracts are dried, evaporated and the residue distilled to give the title 
compound as a pale yellow oil bp 120.degree./0.25 mm.