A Novel Degydrative Ring-Transformation of 1-Alkyl-3-aroypyrrolidenes into 1-Alkyl-2-aryl-3-methylpyrroles
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When heated in an alcoholic solvent, such as ethylene glycol or butanol, 4-substituted 3-aroyl-1-alkylpyrrolidines, which are readily accessible via the condensation of an amino acid, paraformaldehyde, and 3-substituted 1-ary-2-propen-1-one, afforded 4-substituted 1-alkyl-2-aryl-3-methylpyrrole derivatives in good yields. The ring-transformation of 3,4-dibenzoyl-1-methyl-2-phenylpyrrolidine occurred in two directions, giving the corresponding 3-benzyl- and 3-methylpyrrole derivative. Also, bicyclic pyrroles, such as 1<i>H</i>,3<i>H</i>-pyrrolo[1,2-<i>c</i>]thiazole, 2,3-dihydro-1<i>H</i>-pyrrolizine, and 5,6,7,8-tetrahydroindolizine, were prepared by the ring-transformation of bicyclic aroylpyrrolidines obtained from the corresponding cyclic amino acids. A mechanism for the ring-transformation is proposed.
- Bulletin of the Chemical Society of Japan
Bulletin of the Chemical Society of Japan 68(7), 1969-1979, 1995-07-15
The Chemical Society of Japan