Selective Copper-Catalyzed Cross-Coupling of Cyclopropyl and Cyclobutyl 1,2-Bis(boronates).

Herein we disclose an approach to perform the selective copper-catalyzed cross-coupling of 1,2-diborylcyclopropanes and cyclobutanes with different electrophiles. In the case of 1,2-diborylcyclopropanes, a simple alkoxide base was needed to promote the cross-coupling with either allyl halides, propargyl halides, alkynyl halides, or electrophilic amines, which highlights the special reactivity of these diboron compounds. In the case of 1,2-diborylspirocyclobutanes, a site-selective activation of the less hindered boron was observed. Further functionalization of the remaining boryl moiety provides access to highly functionalized stereodefined cyclopropanes and spirocyclobutanes.