Diastereoface Selectivity During Pthalimidonitrene Additions to (E)-and (Z)-configurated ?, ?-unsaturated esters, induced by a chiral center in the ?-position
ribo-, and lyxo- configuration, respectively, by X-ray structure analysis of 2b, 2d, and 6a. The diastereofaceselectivity of the nitrene additions, induced by the chiral substructure around C(γ), resulted in more 2 than 3 from 1, but more 6 than 5 from 4, which means that the preference of attack at the double bond switches from one side to the other depending on the C=C configuration. The preferences
A new method for the preparation of optically active five-membered cyclic carbonates bearing an unsaturated substituent via an enzymatic reaction is described. In the examination of the regiospecific recognition of PPL, dl-(E)-4-(1-octenyl)-1,3-dioxolan-2-one is hydrolyzed with higher enantioselectivity. The reaction is also applicable to the racemic (E)-4-[2-(alkoxycarbony)ethenyl]-1,3-dioxolane-2-one