Direct Carboboration of Aryl Alkenes with Stable Organoborons Through Ziegler-Type Addition.

Carbometallation reaction represents a classic strategy for the bifunctionalization of unsaturated hydrocarbons, yet conventional implementations predominantly rely on either highly reactive organometallic reagents or transition metal catalysts. Notably, the direct employment of metalloid organoboron reagents for such addition processes remains elusive except when specific substrate combinations are employed. Herein, a base-catalyzed carboboration reaction of aryl alkenes with bench-stable benzylic boronates is reported. This anionic-based strategy is not only applicable to the carboboration of substituted styrenes but also to vinyl cyclopropanes and vinyl cyclobutane, affording the corresponding 1,5- and 1,6-carboboration-related products. Combined experimental and computational investigations reveal a mechanism that involves the Ziegler-type carbometallation process. The synthetic utility is further highlighted by the facile one-pot derivatization of the resulting benzylic boronates. Furthermore, a modified catalytic system offers an alternative to the anionic polymerization of styrene.