NMR studies of three types of highly coordinated organotin hydrides: Chemo-, regio-, and stereoselective reduction of 2,3-epoxy ketones

Three types of highly coordinated organotin hydrides, Bu(2)SnIH-Lewis base (Lewis bases; HMPA or tripiperidinophosphine oxide) (type A), Bu(2)SnFH-HMPA (type B), and Bu(3)SnH-Bu(4)NX (X = F, CN) (type C), were characterized as nucleophilic, chelation, and nonchelation types of reductants, respectively, in the reaction with 2,3-epoxy ketones 1. These reagents, which promoted a reduction of the epoxy ring and syn-selective and anti-selective carbonyl reduction, respectively, were spectroscopically confirmed with H-1, C-13, F-19, and Sn-119 NMR and FT-IR. Furthermore, the correlations between their structures and selective reducing abilities were discussed.