Au(I)-Catalyzed Formal Intermolecular Carbene Insertion into Vinylic C(sp<sup>2</sup>)–H Bonds and Allylic C(sp<sup>3</sup>)–H Bonds
Xiao‐Yuan Cui, Zhong-Tian Ye, Haihong Wu, Changge Ji, Feng Zhou, Jian Zhou
Abstract
We report a metal-catalyzed formal intermolecular carbene insertion into the vinylic C(sp 2 )–H bond of alkenes, wherein Au(I) proved to be more efficient than the other metal catalysts screened. This provides facile access to C4-alkenyl isochromanones and isoquinolinones from the corresponding diazo reagents and α-methylstyrenes in moderate to good yields and excellent chemoselectivity. Mechanistic studies suggested two possible reaction pathways simultaneously exist, the gold-carbenoid participating nucleophilic attack-selective elimination and a cyclopropanation–ring-opening–olefin isomerization process. The structure of diazo reagents has a great impact, as diazo(thio)oxindoles react with α-methylstyrenes via the formal allylic C(sp 3 )–H insertion to afford 3-allyl(thio)oxindoles.