Synthesis and Aldol Stereoselectivity of 2-Oxazolidinones Derived from <scp>l</scp>-Histidine

Abstract

Abstract The regiospecific synthesis of the 2-oxazolidinones 5b, 7, 12a, and 12b starting from l-histidine la is described. The stereoselectivity in the dibutyl(trifluoromethylsulfonyloxy)borane promoted aldol condensation between the chiral imides 13a and 13b and benzaldehyde was also studied. The formation of a cationic imidazole–boron complex, 14a, occurs before the aldol condensation between 13a and benzaldehyde takes place. However, the condensation between 13b and benzaldehyde occurs without the formation of any boron complex. The steric hindrance of the substituent at C-4 may account for this difference in behavior.