Synthesis of Cyclobutenes by Highly Selective Transition-Metal-Catalyzed Ring Expansion of Cyclopropanes


  • We thank the University of Wisconsin for startup funding and the Analytical Instrument Center (AIC) for NMR support.


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A highly chemoselective, regioselective, and stereospecific synthesis of polysubstituted cyclobutenes, by catalyst-controlled ring expansion of cyclopropanes via metal carbene intermediates, is reported. Transition-metal catalysts showed profound effects on the reactivity and selectivity of metal carbene intermediates in this ring-expansion reaction.