Tscherniac‐Einhorn Reaction

Abstract

An acid‐promoted aromatic nucleophilic alkylation by using N ‐hydroxymethyl amide or N‐ hydroxylmethylimide as the alkylating reagent is referred to as the Tscherniac–Einhorn reaction and Likewise, the N ‐hydroxymethylamide and N ‐hydroxymethylimide are referred to as the Tscherniac–Einhorn reagents. This reaction is usually promoted by a strong acid. In addition, it has been found that the yield increases from 40% to 65% when the ratio of H 2 SO 4 to o ‐chlorobenzoic acid is doubled. Currently, the dehydration of N ‐hydroxymethylamides is still the common method for forming N ‐acyliminium ions. The preparation of N ‐hydroxymethylamides has been improved by condensation of the amides with aqueous formaldehyde in dioxane in the presence of excess NaOH. This reaction is very useful for the preparation of some alkaloid derivatives.