γ-Substituted Butanolides from Cyclopropane Hemimalonates: An Expedient Synthesis of Natural (<i>R</i>)-Dodecan-4-olide
作者:Huck K. Grover、Michael R. Emmett、Michael A. Kerr
DOI:10.1021/ol402252u
日期:2013.9.20
hemimalonates has led to the facile synthesis of γ-substituted butanolides. Under microwave irradiation, cyclopropane hemimalonates undergo rapid conversion to butanolides in the presence of inorganic salts with an unprecedented retention of stereochemistry. This unique process has been applied to the total synthesis of the naturally occurring (R)-dodecan-4-olide.
Enamines of type 1 with anion-stabilizing substituents a are available by Horner-reaction of suitable phosphonates with aldehydes. Deprotonation of 1 gives aminoallyl anions 2, which react with carbonyl compounds (depending on a) either to butyrolactones 8 resp. 10 or to 6-membered lactons 13. This process amounts to synthesis of lactones from two carbonyl compounds and an α-aminosubstituted phosphonate