STEREOCONTROLLED CYCLOPROPANATION OF ALPHA,BETA-UNSATURATED CARBOXAMIDES DERIVED FROM BICYCLIC AMINO-ALCOHOLS

The asymmetric cyclopropanation of the exo-N-[(1R,2S,3R,4S)-2-hydroxy-1,7,7-trimethylbicyclo[2.2.1]hept-3-yl]-3-phenyl-2-propenamide and the endo-( 1R,2R,3S,4S)-isomer with Et(2)Zn/CH2I2 proceeded with predictable absolute stereochemistry. The exo-amide gave the (1R,2R)-cyclopropane derivative selectively (de less than or equal to 80%), while the endo-amide gave the (1S,2S)-isomer (de less than or equal to 58%). Complete reversal of the stereoselectivity (98% de) was observed when O-triisopropyl derivatives of the amides were used in the cyclopropanation.