| abstract |
Compounds of the formula (I)(in which X represents HS- or a group R,R<sub>2</sub>N- wherein R, and R<sub>2</sub> which may be the same or different represent hydrogen or a straight or branched chain alkyl group containing from 1 to 4 carbon atoms or a benzyl group and R<sub>3</sub> represents a C<sub>3-2</sub> alkyl group or a C<sub>3-2</sub> cycloalkyl group) are prepared by reacting an α-ketoester of the formula (II)(in which Alk represents an alkyl group) or a precursor thereof with a compound of the formula (III)The precursor of the compound of formula (II) may be a mixture of isomeric enol estersThe compounds of formula (I) may be converted into compounds of formula (VIII)in which R, and R<sub>2</sub> which may be the same or different represent hydrogen or a straight or branched chain alkyl group containing from 1 to 4 carbon atoms, and R<sub>3</sub> is as defined above. |