Nitration reactions of conjugated compounds employing lithium nitrate / TFAA

Tandem nitration and Ritter reaction of three conjugated dienes using trifluoroacetyl nitrate in acetonitrile led predominantly to 1,4-addition products and concomitant N-nitration. The major products, N-nitro-N-(4-nitrobut-2-enyl)acetamide derivatives, were obtained in 57%-70% yield. Tandem nitration and Ritter reaction of 4-methylpent-3-en-2-one led to the 1,2-addition product, a base-sensitive alpha-nitroketone. Nitration of N-methylacetamide and pyrrolidine by trifluoroacetyl nitrate occurs on the N-atom, whereas nitration of N-phenylacetamide occurs on the aromatic ring.