Rhodium(II)-carbenoid C–H insertion reactions in the synthesis of α,β′-dioxospirane systems

Abstract

Spiro[4.4]nonane-, spiro[4.5]decane- and spiro[4.6]undecane-α,β′-diones have been prepared from 1-diazo-4-(2,2-ethylenedioxycycloalkan-1-yl)butan-2-one intermediates by Rh₂(OAc)₄- and Rh₂(TPA)₄-catalyzed C–H insertions. Competitive insertions also gave trans-bicyclic derivatives. The relative stereochemistry in bicyclic derivatives has been determined by single crystal X-ray analyses.