A General Process for the Haloamidation of Olefins. Scope and Mechanism

A methodology is described for the addition of a bromine atom and an amide nitrogen in a trans sense to an olefinic double bond. The process, which is illustrated by numerous examples, involves the use of an N-bromoamide and a Lewis acid as a source of Br+ which reacts with the olefin. The amide group is derived from a nitrile and a water molecule which serve as nucleophiles for the overall three-component reaction. The bromoamidation is general for a broad range of olefins and nitriles. This reaction pathway provides access not only to vicinal bromoamides but also to N-acyl aziridines and oxazolines. From these, many types of amines and amino alcohols can be prepared. Examples are provided which delineate diastereo- and regioselectivity preferences. An analogous chloroamidation reaction is also described.