Preparation of methylfuro[3,4-b] [1,4]benzodioxinones as intermediates for the synthesis of substituted polycyclic systems. Importance of the acid used as catalyst

Article abstract of DOI:10.1016/S0040-4020(99)00670-5

The lactones 10 and 11 were conveniently prepared in excellent yield by reaction of the corresponding γ-hydroxy amides 6, 7 and 8 in the presence of propionic acid in catalytic amounts. By increasing the ratio of propionic acid used, under the same reaction conditions, the hydroxy amide 6 reacted to give a mixture of ketoamides 13 (cis/trans).