Chemistry of pyrrolizines; reactions with cyanogen bromide and trifluoroacetic anhydride

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Abstract

Interaction of the pyrrolizine 3 with cyanogen bromide in a tetrahydrofuran/water mixture affords addition to the enamine double bond with formation of 5 which can be aromatized to 6 by silica gel. Reaction of 6 with cyanogen bromide in the same solvent mixture yields the indoline 8a which structure is proved in a chemical way by conversion of the product into the aldehyde 8d. The different reaction pathway is discussed in terms of steric hindrance by the ester groups. Treatment of 6 with trifluoroacetic anhydride gives the trifluoroacetylated compound 11. Removal of the sterically hindered ester groups in 6, with acetic acid in quinoline at 200°, is accompanied by the simultaneous decarboxylation to yield the pyrrolo[1,2-a]indole 13
Original languageUndefined
Pages (from-to)1831-1835
JournalTetrahedron
Volume38
Issue number2
DOIs
Publication statusPublished - 1982

Keywords

  • IR-68995

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