THE STEREOSELECTIVE ADDITION OF ORGANOMETALLIC REAGENTS TO ELECTRON-DEFICIENT ALKYLIDENECYCLOHEXANES - ALTERNATIVE LINKAGES FOR CHOLAPHANE SYNTHESIS

Knoevenagel condensations between t-butylcyclohexanone and malononitrile, Meldrum's acid and ethyl cyanoacetate gave electron-deficient alkenes which underwent equatorial-selective attack by chemoselective aryl organometallic reagents. Further transformations of the products were shown to be possible in some cases. The methodology is relevant to the synthesis of macrocyclic "cholaphane" receptors with externally-directed functional groups.