Gilchrist, Thomas L.Lemos, A.2012-03-092012-03-091993Journal of the Chemical Society, Perkin Transactions 1, 13, 1391-1391, 1993.0300-922XAUT: ALE01411;http://hdl.handle.net/10400.1/936The reaction of ethyl 2-nitrosopropenoate 2a with 1 -methylpyrrole, 2.5-dimethylpyrrole and 2.5- diphenylpyrrole has been investigated. In every case the products result from highly regioselective attack at C-2 of the pyrrole by the electrophile. The azopropenoate esters 2b and 2c react similarly with pyrroles, to the extent that even 1 -(triisopropylsilyl)pyrrole is attacked exclusively at the 2-position by the azo ester 2b. In contrast, the nitrile oxide ethyl cyanoformate N-oxide 12 reacts at the 3-position of 2.5- dimethyl- and of 2,5-diphenyl-pyrrole. The reactions of the nitroso and azo esters with pyrroles are interpreted as Diels-Alder cycloadditions with inverse electron demand.engDiels-AlderHeterocyclesazoalkenejournal article2012-02-27