Enantioselective Construction of Oxa- and Aza-Angular Triquinanes through Tandem [4 + 1]/[3 + 2] Cycloaddition of Sulfur Ylides and Nitroolefins

A formal [4 + 1]/[3 + 2] cycloaddition sequence of sulfur ylides and alkene-tethered nitroolefins has been developed. The use of (R)-binol-derived chiral sulfide leads to an asymmetric process that allows the construction of oxa- and aza-angular triquinanes in good to excellent diastereo- and enantioselectivities.