Cyanide ion cocatalysis in Ti(salen) catalysed asymmetric cyanohydrin carbonate synthesis

摘要

In the presence of potassium cyanide or the potassium cyanide/ 18- crown- 6 complex as a cocatalyst, 1 - 2 mol% of titanium( salen) complex 1 catalyses the asymmetric addition of achiral cyanoformates to aldehydes, giving cyanohydrin carbonates with high enantiomeric excesses; and catalyses the diastereoselective addition of chiral cyanoformates derived from alpha- methyl-benzyl alcohol to aldehydes, a reaction which exhibits double asymmetric induction.