Highly Z- and enantioselective ring-opening/cross-metathesis reactions catalyzed by stereogenic-at-Mo adamantylimido complexes.

The first highly Z- and enantioselective class of ring-opening/cross-metathesis reactions is presented. Transformations are promoted in the presence of <2 mol % of chiral stereogenic-at-Mo monoaryloxide complexes bearing an adamantylimido ligand that are prepared and used in situ. Reactions involve meso oxabicyclic substrates and afford the desired pyrans in 50-85% yield and up to >98:<2 enantiomer ratio. Importantly, the desired chiral pyrans thus obtained bear a Z olefin either exclusively (>98:<2 Z/E) or predominantly (>or=87:13 Z/E).