GB911481A - New thiophane derivatives and process for their production - Google Patents

Abstract

The invention comprises thiophane derivatives of the general formula <FORM:0911481/IV (b)/1> wherein R represents hydrogen or an alkyl or cycloalkyl radical having from 1 to 6 carbon atoms, X represents a hydroxy radical and Y represents a hydrogen atom or X and Y together represent an oxo radical, and Z represents a monovalent anion or an equivalent of a polyvalent anion, and the preparation thereof by reducing a thiophane derivative of the general formula <FORM:0911481/IV (b)/2> wherein X1 represents a hydroxy radical and Y1 represents a hydrogen atom or X1 and Y1 each represent an alkoxy radical or together represent an oxo radical or an alkylenedioxy radical and R has the above significance, with aluminium hydride in an amount sufficient to reduce the amide radical and any oxo radical present, the treatment being performed in an ether like solvent, converting aketal reaction product which contains a 3-dialkoxy or alkylenedioxy substituent, advantageously by acid hydrolysis or transketalisation, into the corresponding free oxo compound, if desired reducing the oxo radical as above to the corresponding 3-hydroxy compound, if desired reacting the oxo or hydroxy compound of the first general formula above with a reactive ester of methanol to form a compound of the second general formula above and, if desired, replacing the anion produced by another anion. The second reduction step above may also be effected with sodium or potassium borohydride or with catalytically activated hydrogen. In the examples hydrochloride salts of the substituted thiophanes of the first general formula above are also prepared. Cis and trans forms of the substituted thiophanes of the second general formula above may be separated by fractional crystallisation of the L-di-p-toluyl tartrates thereof. Thiophanes of the general formula <FORM:0911481/IV (b)/3> wherein X1 and Y1 each represent an alkoxy radical or together represent an alkylenedioxy or oxo radical and R have the above significance, are prepared by esterifying the required 2-R substituted -3-oxo-5-carboxylic acid to form the corresponding 5-carboxylic acid ester when required acetalising the oxo group, to form a 3-dialkoxy (or 3-alkylenedioxy)-2R-substituted-5-carboxylic acid ester, and finally heating the 5-carboxylic ester with dimethylamine. 2-R-substituted-3-oxo-thiophane-5-carboxylic acids wherein R represents an alkyl or cycloalkyl radical having 1 to 6 carbon atoms, are prepared by reacting the required a -R-substituted-a -thioacetic acid alkyl esters and maleic acid dimethyl ester and cyclising the products, saponifying and decarboxylating the resulting 2 - R - substituted - 3-oxo-thiophane-4,5-dicarboxylic acid dimethyl esters.