Directed Regioselective Carbometallation of 1,2‐Dialkyl‐Substituted Cyclopropenes

A regio‐ and diastereoselective copper‐catalyzed carbomagnesiation of 1,2‐dialkylated cyclopropenes is reported. The regioselectivity is controlled by a subtle tethered Lewis basic moiety. The chelating moieties allow the differentiation between two electronically tantamount organometallic intermediates. Further functionalization grants access to polysubstituted stereodefined cyclopropanes bearing up to five alkyl groups. The copper‐catalyzed carbomagnesiation reaction of cyclopropenes is a well‐established method for the synthesis of stereodefined cyclopropanes. All existing reports to date proceeded towards the formation of the electronically more stable organometallic intermediate. Herein we report a regioselective addition to 1,2‐dialkyl‐substituted cyclopropene possessing a tethered directing group to direct the organometallic species towards the formation of single regioisomer intermediate out of two electronically unbiased possibilities.