Borane catalysed ring opening and closing cascades of furans leading to silicon functionalized synthetic intermediates

Abstract

The conversion of renewable biomass resources to synthetically valuable chemicals is highly desirable, but remains a formidable challenge in regards to the substrate scope and reaction conditions. Here we present the development of tris(pentafluorophenyl) borane-catalysed conversion of furans via ring-opening and closing cascade processes to afford siliconfunctionalized synthetic chemicals under transition metal-free conditions. The furan ring-opening with hydrosilanes is highly efficient (TON up to 2,000) and atom-economical without forming any byproduct to give rise to a-silyloxy-(Z)-alkenyl silanes. Additional equivalents of silane smoothly induce a subsequent B(C6F5)(3)-catalysed cyclization of initially formed olefinic silane compounds to produce anti-(2-alkyl) cyclopropyl silanes, another versatile synthon being potentially applicable in the synthesis of natural products and pharmacophores.