Organocatalytic Enantioselective Michael Addition of 2,4-Pentandione to Nitroalkenes Promoted by Bifunctional Thioureas with Central and Axial Chiral Elements
摘要:
Two novel bifunctional amine-thiourea organocatalysts 1 and 2, which both bear central and axial chiral elements, have been developed to promote enantioselective Michael reaction between 1,3-dicarbonyl compounds and nitro olefins. The catalyst 2 afforded the desired products with good levels of enantioselectivity (up to 96% ee), showing clearly that two chiral elements of 2 are matched, and enhance the stereochemical control.