Synthesis of novel indolizine derivatives

The reaction of a number of γ-butyrolactones with azole anions is shown to give γ-substituted butanoic acids in moderate to good yields. The pyrrolyl and indolylbutanoic acids obtained underwent cyclization in a simple one-pot procedure employing ethyl chloroformate and boron trifluoride etherate. Some aspects of the chemistry of the resulting indolizin-8-ones are described.