Reactions of Functionalized 2-Vinylpyrroles with Amines

SCHEME 2.97 Instant cyclization of l-alkylthio-2-cyanovinylpyrroles in the presence of KOH in MeOH. 

SCHEME 2.98 Cyclization of functionalized 2-(l-ethylthio-2-cyanovinyl)-4,5,6,7-tetrahy-droindoles in the presence of Et3N. 

Despite the poor yield of pyrrolizine with carbamoyl moiety 28b and the corresponding configuration of vinylpyrrole 27b, the reaction remains chemoselective among two functional groups capable of participating in the cyclization (amide and nitrile), only the latter is active. 

Similar aminopyrrolizines have been obtained by substitution of the methylthio group in 2-(2,2-dicyano-l-methylthiovinyl)pyrrole with secondary amine and the subsequent cyclization of 2-(l-amino-2,2-dicyanovinyl)pyrrole 29 in the presence of tertiary amine [575]. 

SCHEME 2.99 Synthesis of l-amino-3-iminopyrrolizines from 2-(l-ethylthio-2,2-dicy-anovinyl)pyrroles or l-ethylthio-3-iminopyrrolizine-2-carbonitriles under the action of the secondary amines. 

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