Cross-electrophile stannylation of alkyl triflates and halides with chlorostannanes enabled by Cr(ii)-phenanthroline catalysis

Abstract

Cross-electrophile coupling has emerged as a powerful strategy for the construction of C–C and C–heteroatom bonds, yet its extension to carbon–metal bond formation is underdeveloped. We report α-cross-electrophile stannylation of alkyl triflates and halides with chlorostannanes that forges C(sp³)–Sn bonds, enabled by a phenanthroline-ligated chromium catalyst under mild conditions. This reductive coupling provides a step-economical route to α-functionalized alkyltin reagents, achieving excellent functional group tolerance, bypassing the need for preformed stannyl organometallic reagents or hydrostannanes via multi-step synthesis. The utility of this strategy was highlighted by the downstream functionalization of eight commercial drug molecules, enabling the synthesis of 10 diverse functionalized molecules by stannyl group interconversion and three derivatives through modifying the appended functionalities. Mechanistic studies suggest that the chromium(II) catalyst reduces aliphatic electrophiles via single-electron transfer to generate α-alkyl radicals, which are captured by Cr(II) and coupled with chlorostannanes to form α-functionalized alkyltin products.