Catalytic dehydrocoupling of amines and boranes by an incipient tin(ii) hydride

Abstract

The facile heterodehydrocoupling of a range of primary or secondary amines and even ammonia with pinacolborane (HBPin) was accomplished using {Ar^Me₆Sn(μ-OMe)}₂ (1, Ar^Me₆ = C₆H₃-2,6-(C₆H₂-2,4,6-Me₃)₂) as pre-catalysts for a catalytically active tin(II) hydride. The more sterically hindered pre-catalyst 2, {Ar^iPr₄Sn(μ-OMe)}₂ (Ar^iPr₄ = C₆H₃-2,6-(C₆H₃-2,6-iPr₂)₂) facilitated the dehydrocoupling only of primary amines with HBPin, and at an increased rate relative to the less crowded {Ar^Me₆Sn(μ-OMe)}₂. Also presented is {Ar^Me₆Sn(μ-NEt₂)}₂ (3), which can be converted into the structurally characterizable {Ar^Me₆Sn(μ-NEt₂)(μ-H)SnAr^Me₆} (4) via the addition of pinacol borane. This, alongside stoichiometric studies, give insight into the mechanism of the catalysis.