Molecular sieve controlled diastereoselectivity: effect in the palladium-catalyzed cyclization of cis-1,2-divinylcyclohexane with .alpha.-oxygen-substituted acids as chiral nucleophiles

Molecular sieves have been shown to improve greatly the stereoselectivity in the palladium(II)-catalyzed reaction of cis-1,2-divinylcyclohene with chiral acids. Reactions run with molecular sieves and derivatives of (R)-lactic acids as nucleophiles always yielded products with S configuration at the newly formed chiral center in contrast to reactions without molecular sieves that gave products with either S or R configuration at this chiral center. It appears that this effect has not been observed previously