Asymmetric catalysis of the [5 + 2] cycloaddition reaction of vinylcyclopropanes and pi-systems

As part of our studies of metal-catalyzed m + n (+...o)] cycloadditions, we have previously reported the rhodium-catalyzed 5 + 2] cycloaddition of vinylcyclopropanes (VCPs) and pi-systems. These studies have led to Rh(I) complexes that catalyze these reactions in minutes at room temperature or in water without organic solvents. We describe a comparative evaluation of several chiral catalysts for the 5 + 2] reaction, evaluation of a preferred catalyst, ((R)-BINAP)Rh]+SbF6-, with substrates differing in substitution and tether types-producing enantiomeric excesses >/=95% for several systems. A predictive model for the selectivity is also presented.