Iron-Catalyzed anti-Selective Carbosilylation of Internal Alkynes

Abstract

Reported is the anti-selective carbosilylation of internal alkynes with silylborane and alkyl halides using a FeBr₂ /DPPE catalyst system. The iron catalyst allows simultaneous introduction of a carbon electrophile and a silicon nucleophile to simple internal alkynes, including diaryl-, dialkyl-, and aryl/alkyl-substituted alkynes, in a highly stereoselective manner. Alkyl halides are applicable as the electrophiles, thereby enabling the synthesis of a variety of tetrasubstituted alkenylsilanes. In addition, syn-selective carbosilylation was achieved through stereoswitching, by using a silylborane having oxygen functionality on the silyl group. This novel iron-catalyzed carbosilylation is a useful tool for expedient synthesis of stereodefined multisubstituted olefins, a fundamental structural motif in organic chemistry.

Keywords: alkynes; halogens; iron; regioselectivity; silylation.