α-Functionalisation of Ketones Through Metal-Free Electrophilic Activation

Abstract

Triflic anhydride mediated activation of acetophenones leads to highly electrophilic intermediates that can undergo a variety of transformations when treated with nucleophiles. This electrophilic ketone activation gives access to α-arylated and α-oxyaminated acetophenones under metal-free conditions in moderate to excellent yields and enables extension to the synthesis of arylated morpholines via generation of vinylsulfonium salts. Computational investigations confirmed the transient existence of intermediates derived from vinyl triflates and the role of the oxygen atoms at the para position of aromatic ring in facilitating their stabilisation.

Keywords: sigmatropic rearrangement; vinyl cations; vinyl triflate; α-arylation; α-oxyamination.