Study on the preparation of heteroaryl substituted enamines. A simple synthesis of heteroaryl substituted acetaldoximes from enamines

Article abstract of DOI:10.1002/jhet.5570330240

A comparative study of the reactivity of methyl groups towards N,N-dimethylformamide dimethyl acetal and tert-butoxybis(dimethylamino)methane was carried out on methyl substituted six-membered nitrogen containing heterocycles 1 to give enamines 2, which were easily transformed to oximes by treating with hydroxylamine hydrochloride in methanol. Most of them were isolated as (E,Z)-oximes of heteroarylacetaldehyde (11), but 5-(1,2,4-triazinyl) substituted derivatives as (E,Z)-oximes of 2,5-dihydro-1,2,4-triazin-(Z)-5-ylideneacetaldehyde (11t, 11u, and 12). Oximes were finally transformed to the corresponding acetonitriles 16 and 3-(dimethylamino)acrylonitriles 17.