Synthesis of 6-Substituted 4-Hydroxy-2-pyrones from Aldehydes by Addition of an Acetoacetate Equivalent, Dess-Martin Oxidation and Subsequent Cyclization
作者:Thorsten Bach、Stefan Kirsch
DOI:10.1055/s-2001-18759
日期:——
A three step procedure for the synthesis of 6-substituted 4-hydroxy-2-pyrones 2 from aldehydes 1 is described. An acetoacetate equivalent 3 was added to the corresponding aldehyde (10 examples) in a vinylogous Mukaiyama aldol addition (72-99%). The intermediate alcohols 4 were oxidized to the ketones 5 using the Dess-Martin method (67%-quant.). A final thermal cyclization of compounds 5 yielded the title compounds 2 (61-92%; 40-85% overall).