Supported chiral Mo-based complexes as efficient catalysts for enantioselective olefin metathesis

摘要

Syntheses and catalytic activities of seven new polymer-supported chiral Mo-based complexes are disclosed. Four of the complexes are polystyrene-based, and three involve polynorbornene supports. Studies concerning the ability of the polymer-bound chiral complexes to promote an assortment of asymmetric ring-closing (ARCM) and ring-opening (AROM) metathesis reactions are detailed. In many instances, levels of reactivity and enantioselectivity are competitive with those of the analogous homogeneous catalysts. The positive effect of lower cross-linking within the polymer backbone on reaction efficiency and asymmetric induction is detailed. The optically enriched products obtained through the use of the supported complexes, after simple filtration and removal of the supported Mo catalysts, contain significantly lower levels of metal impurities as compared to products synthesized with the corresponding homogeneous catalysts.