Expanding the limits of catalysts with low-valent main-group elements for the hydroboration of aldehydes and ketones using [L†Sn(ii)][OTf] (L† = aminotroponate; OTf = triflate)

Abstract

A triflatostannylene [L^†Sn(II)][OTf] (2) is reported here as an efficient catalyst with low-valent main-group element for the hydroboration of aldehydes and ketones (L^† = aminotroponate). Using 0.025–0.25 mol% of compound 2, hydroboration of various aldehydes and ketones is accomplished in 0.13–1.25 h at room temperature; the aliphatic aldehydes show an impressive TOF of around 30 000 h⁻¹. DFT calculations are performed to explore the mechanistic aspects of this reaction suggesting that the reaction proceeds via a stepwise pathway with hydridostannylene [L^†Sn(II)H] (2a) as the active catalyst and the H atom transfer from the Sn–H bond to the carbonyl carbon being the rate determining step.