Chiral ligands containing heteroatoms. 11. Optically active 2-hydroxymethyl piperazincs as catalysts in the enantioselective addition of diethylzinc to benzaldehyde
(2R,5S) and (2S,5S)-2-hydroxymethyl-5-alkyl piperazines 1–5 were prepared in good yields without any racemization. The use of these compounds as chiral catalysts for the enantioselectiveaddition of diethylzinc to aldehydes is described. This paper reports the first example of the use of piperazine methanols in asymmetric synthesis.