Stereoselective hydrostannation of substituted alkynes initiated by triethylborane and reactivity of bulky triorganotin hydrides

Abstract

This paper reports the results obtained in a study on the radical hydrostannation of mono- and disubstituted alkynes with bulky triorganotin hydrides using triethylborane as initiator. The addition of trineophyl- ( 1), tris[(phenyldimethylsilyl)methyl]- ( 2), and 9-tripticyldimethyltin ( 3) hydride to eight alkynes was carried out at room temperature leading to vinylstannanes in good to excellent yields and, mostly, with complete stereoselectivity. The results obtained in a study on the relative reactivity of trineophyl- ( 1), tris[(phenyldimethylsilyl)methyl]- ( 2), 9-triptycyldimethyltin ( 3) hydrides, and tri- n-butyltin hydride ( 29) using the radical reactions between these hydrides and 6-bromo-1-hexene ( 28) are also reported. Full 1H-, 13C-, and 119Sn NMR characteristics are included.