Amines <i>vs. N</i>‐Oxides as Organocatalysts for Acylation, Sulfonylation and Silylation of Alcohols: 1‐Methylimidazole <i>N</i>‐Oxide as an Efficient Catalyst for Silylation of Tertiary Alcohols

Abstract

Abstract A comparison of the relative catalytic efficiencies of Lewis‐basic amines vs. N ‐oxides for the acylation, sulfonylation and silylation of primary, secondary and tertiary alcohols is reported. Whilst the amines are generally superior to the N ‐oxides for acylation, the N ‐oxides are superior for sulfonylation and silylation. In particular, 1‐methylimidazole N ‐oxide (NMI‐O) is found to be a highly efficient catalyst for sulfonylation and silylation reactions. To the best of our knowledge, NMI‐O is the first amine or N ‐oxide Lewis basic organocatalyst capable of promoting the efficient silylation of tert ‐alcohols in high yield with low catalyst loading under mild reaction conditions. magnified image