Stereoselective two-step chemical preparation of 1,4-dialkyl-1,4-dimethoxycyclohexa-2,5-dienes

The reaction of p-benzoquinone (1) with several organolithium compounds (methyl- ethyl- n-butyl-, phenyllithium) led after hydrolysis with water to the corresponding crude diols 4 which were successively treated with sodium hydride and methyl iodide yielding the expected 1,4-dialkyl-1,4-dimethoxycyclohexa-2,5-dienes 2a-d in a stereoselective manner. The use of a tandem process with two different organolithium reagents followed by methylation by the same procedure yielded stereoselectively the mixed 1-alkyl-4-alkyl' derivatives 2e,f.