Reversal of facial selectivity in complex Diels-Alder reactions

摘要

A complex Diels-Alder reaction between a semi-cyclic diene with allylic silyloxy substituents and a bromo enone presented an unusual diastereoselectivity:attack of the diene occured on its more hindered face,and this reversal of selectivity was shown to be induced by the presence of a bromo substituent in the dienophile.