An investigative study of kinetic resolutions by the Sharpless asymmetric dihydroxylation reaction

The requirements for a highly selective kinetic resolution with the Sharple ss asymmetric dihydroxylation (AD) reaction were investigated with a number of alkene substrates. It was found that with 1-phenyl-4-tert-butylcyclohex ene enantioselectivity is very high, yet diastereoselectivity is poor and k inetic resolution is ineffective. With 5-methyl-2-phenylbicyclo[3.2.0]hepta n-2-ene both diastereoselectivity and enantioselectivity are high and kinet ic resolution is effective. It was discovered that the transition state for the product-determining step in the Sharpless AD reaction is not product-l ike, and effective kinetic resolution can occur when one face of a chiral a lkene is hindered. (C) 2001 Elsevier Science Ltd. All rights reserved.