Results Synthesis.(E)-and (Z)-tert-butyl methyl (a-bromo-p-methylbenzy1idene) malonate (7a and 7b) and the p-nitro analogues 8a and 8b were available from a previous Mild hydrolysis of the tert-butyl ester without double-bond isomerization followed by esterification with CD2N2 should therefore be a stereospecific route to both 4 and 5 and their Z isomers. However, mild hydrolysis of 7a with dilute trifluoroacetic acid gave both acids 9a and loa. ...
