ALPHA,ALPHA' ANNELATION OF CYCLIC KETONES . SYNTHESIS OF BICYCLO[3.2.1]OCTANE DERIVATIVES

Reaction of cyclopentanone enamine with ethyl α-(l-bromomethyl)acrylate affords ethyl bicyclo[3.2.1]octan-8-one-3-endo-carboxylate. The reaction generally follows a pathway including alkylation and proton transfer to re-form an enamine, followed by Michael reaction. The preparation of trans-diaxial bicyclo[3.2.1]octanone diesters from γ-bromomesaconic ester and benzobicyclo[3.2.1]octanones from indanone is described. Proof of stereochemistry of these molecules reflects upon the mechanism of the reaction and provides interesting intermediates for further study. © 1969, American Chemical Society. All rights reserved.