Patent GB-768840-A (GB)
Title: Compounds containing a cyclopentyl ring
IPC: C07D211/88
Filed: 1953-11-30
Abstract: The invention comprises compounds of the formula <FORM:0768840/IV(b)/1> (wherein R1 is CH2 or -CH2CH2-, R2 is an alkyl radical (including cyclo-alkyl and aralkyl), an aryl radical or a heterocyclic radical and the radical R2 may contain substituents) and the corresponding cyclopentenyl compounds wherein the cyclopentyl radical contains a double bond in the 2,3-position.  Such compounds are obtained by condensing a cyclopentyl- or cyclopentenyl-malonic ester, -acetoacetic ester or -cyanoacetic ester with chloracetic or chloropropionic ester and heating the resulting product (the anhydride) with an amine of the formula R2NH2.  Alternatively a cyclopentyl- or cyclopentenyl malonic ester, -acetoacetic ester or -cyanoacetic ester is condensed with chloracetic or chloropropionic nitrile and the imide obtained is heated in the presence of an alkali metal or its amide or alkylate with a halide of the formula R2X. Cyclopentenyl derivatives may then be hydrogenated to the corresponding cyclopentyl compounds.  In examples: (1) cyclopentenylsuccinic acid anhydride and methylamine are reacted to form cyclopentenyl-succinic acid methyl imide; (3) cyclopentyl-succinic acid imide and ethyl bromide are reacted in the presence of sodium to give cyclopentyl-succinic acid-N-ethyl-imide. Similarly to (1) are prepared (2) cyclopentyl-succinic acid methyl-imide; (4) cyclopentenyl-succinic acid-N-ethyl-imide (cyclopentenyl-succinic acidethylamido acid being an intermediate); (6) cyclopentyl-succinic acid-N-butyl-imide; (7) cyclopentyl-succinic acid-N-allyl-imide (cyclopentyl - succinic acid - N - allyl - amido acid being an intermediate); (8) cyclopentyl-succinic acid - N - phenyl - imide; (9) cyclopentenyl - succinic acid - g  - (piperidyl) - propyl - imide; (10) cyclopentenyl - succinic acid - N - benzyl - imide; (11) cyclopentencyl - glutaric acid - N - methyl-imide; (via cyclopentencyl glutaric acid methylamido acid); (12) cyclopentyl glutaric acid N-methyl-imide; (13) cyclopentenyl-glutaric acid-N-methyl-imide; (14) cyclopentyl-glutaric acid-N-ethylimide; (15) cyclopentenyl - glutaric acid - N - butyl - imide (via cyclopentenyl-glutaric acid-butylamido acid, which is treated with acetyl chloride); (16) cyclopentyl - glutaric acid - N - butyl - imide (via cyclopentyl - glutaric acid - n - butylamido-acid); (18) cyclopentenyl-glutaric acid-N-benzyl-imide (via the amido-acid); (19) cyclopentyl - glutaric acid - N - benzyl - imide; (20) cyclopentenyl - glutaric acid - N - phenyl - imide; (21) cyclopentyl - glutaric acid - N - phenyl - imide; (22) cyclopentenyl-glutaric acid - N-(p-chlorophenyl) imide; (23) cyclopentyl-glutaric acid - N - (p - chlorophenyl) imide; (24) cyclopentenyl - glutaric acid - N - (p - methoxyphenyl) - imide; (25) cyclopentyl - glutaric acid-p-methoxyphenyl-imide; (26) a -cyclopentenyl - glutaric acid - N - a  - pyridyl - imide; (27) a -cyclopentyl-glutaric acid-N-a -pyridyl-imide.  In Examples (18) to (27) the amido-acid is formed as an intermediate.  Similarly to Example (3) are prepared (5) cyclopentenyl-succinic acid - N - butyl - imide; (17) a -cyclopentenyl - glutaric acid - N - (diethyl - aminoethyl) - imide; a  - cyclopentenyl - glutaric acid-N-(piperidinoethyl) imide and the corresponding cyclopentyl derivatives.  Starting materials. Cyclopentenylmalonic acid diethyl ester (sodium compound) is reacted with ethyl bromoacetate to form the triethyl ester of carboxy-cyclopentenyl-succinic acid which on saponification to the acid, decarboxylation and distillation gives cyclopentenyl-succinic anhydride.  Cyclopentylsuccinic acid is prepared by a similar series of reactions.  The triethyl ester of carboxy-pentyl-succinic acid is also prepared by hydrogenation of the corresponding cyclopentenyl derivative. Cyclopentenylaceto-succinic acid diethyl ester (from the reaction of the sodium compound of cyclopentenylaceto-acetic acid ester and ethyl bromoacetate) is heated with caustic soda lye to give cyclopentenyl-succinic acid, which is converted to the anhydride by distillation.  Cyclopentenylcyanosuccinic acid diethyl ester (from the reaction of cyclopentenylcyanoacetic acid ethyl ester with ethylbromoacetate) is heated with caustic soda lye.  The triethyl ester of carboxy-cyclopentenylglutaric acid (from the reaction of ethyl b -chloropropionate with the sodium salt of cyclopentenylmalonic acid ethyl ester) is saponified, the free acid is decarboxylated to cyclopentenyl glutaric acid, and the latter is converted to the anhydride.  The corresponding cyclopentyl compounds are formed by a similar series of reactions.  The triethyl ester of carboxycyclopentyl-glutaric acid is also obtained by hydrogenation of the corresponding cyclopentenyl derivative. Cyclopentenyl-acetoglutaric acid diethyl ester from the reaction of b -chloropropionic acid) with the sodium compound of cyclopentenylacetoacetic ester) heated with caustic soda lye gives cyclopentenyl-glutaric acid.