On the Hydrostannylation of Aryl Propargylic Alcohols and Their Derivatives: Remarkable Differences in Both Regio- and Stereoselectivity in Radical- and Nonradical-Mediated Transformations.

Herein, we describe a highly regio- and stereoselective radical-mediated and molecular-oxygen (O2 )-dependent hydrostannylation of phenyl propargylic alcohols and their derivatives. There is a significant steric effect on the stereoselectivity of the tin-radical addition. Further, the uncatalyzed regio- and stereoselective hydrostannylation of aryl propargylic alcohols with nBu3 SnH and Ph3 SnH is also described and occurs with near titration kinetics. Although the uncatalyzed addition with nBu3 SnH gave a remarkable γ-regioselectivity irrespective of the electronic nature of the aryl moiety, addition with Ph3 SnH appears to be driven by the electronic nature of the aryl alkynes.