The new method for introduction of an allyl group into the angular position of 2-(TBS-oxymethyl)-2,3,4,6,7,8-hexahydro-1-benzopyran-5-one and its application to chiral Wieland-Miescher type compound synthesis

The stereoselective introduction of an allyl group into the angular position of 2-(TBS-oxymethyl)-2,3,4,6,7,8hexahydro-l-benzopyran-5-one was accomplished using Birch reduction and an enolate trapping reaction. It was determined that the allyl group was introduced via an unexpected conformation-flipped from the initially formed one. Two diastereomeric Wieland-Miescher type compounds, having the allyl group at the angular position, were synthesized as optically pure forms.