Atom-Economic Catalytic Direct Substitution of N,O-Acetals with Simple Ketones
Résumé
A general and powerful catalytic protocol for the direct amidoalkylation of simple enolizable ketones is described, with use of the Lewis superacid Sn(NTf2)4 as a catalyst under thermal conditions. A complete and rational study directed towards the development of efficient conditions for the coupling of a wide range of reaction partner combinations, including the most recalcitrant ones, is presented. The synthetic potential of the reaction is demonstrated through the use of a large set of both carbonyl and N,O-acetalic substrates, providing the corresponding amidoalkylated ketones in 49–99 % yield, by using very low catalyst loadings (≤ 1 mol-%). © 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim