Asymmetric [4+2] cycloadditions employing 1,3-dienes derived from (R)-4-t-butyldimethyl-silyloxy-2-cyclohexen-1-one

1,3-Dienes derived from (R)-4-t-butyldimethylsilyloxy-2-cyclohexen-1-one react with activated dienophiles to form predominately (or sometimes exclusively) syn/endo products. These controlled [4+2] cycloadditions increase the asymmetric complexity from one asymmetric center in the starting material to five asymmetric centers in the products in a single step, and provide a powerful approach for the asymmetric synthesis of compounds containing the bicyclo[2.2.2]octanone carbon skeleton.