Stereo- and enantioselective routes to functionalised cyclohexenes via heterodiene cycloadditions of 6-oxocyclohexene-1-carbaldehydes with ketene acetals

Article abstract of DOI:10.1016/S0040-4020(99)00764-4

Various substituted cyclohexenes related to α-cyclocitral have been prepared using the heterodiene cycloadditions of 2-formyl-4,4-dimethyl-2- cyclohexen-1-one 4 with ketene acetals as the pivotal step. The key intermediates are accessible in homochiral form via an auxiliary-based sequence in which a C₂-symmetric ketene acetal derived from 1,2-bis(2- methylphenyl)ethane-1,2-diol 2a serves as the 2π component. The diol 2a can be recovered in optically pure form.