Regioselective Spiroannulations of α-Acetyl Lactones
作者:Jens Christoffers、Heiko Oertling、Wolfgang Frey
DOI:10.1002/ejoc.200300009
日期:2003.5
Monocyclic spiroannulation precursors 3a−c were obtained by Michael reactions of α-acetyllactones 6a−c with methyl vinyl ketone (7). The selective formation of either regioisomer of both β-oxo (5a−c) and δ-oxo (4a−c) lactones from 3a−c was achieved by varying the reaction conditions. The δ-oxo lactones 4a−c were obtained under basic (buffered) conditions in a pyrrolidine/AcOH system. Under acidic