Enantioselective alkynylation of aldehydes catalyzed by [2.2]paracyclophane-based ligands.
[reaction: see text] [2.2]Paracyclophane-based ketimine ligands were evaluated as catalysts for the enantioselective addition of in situ-prepared alkynylzinc reagents to aldehydes. The initial high activity and enantioselectivity of these ligands could be improved by an additive screening. The final protocol gives chiral propargyl alcohols in up to >98% ee.
Dahmen
Stefan
S
cynora GmbH, Kaiserstr. 100, D-52134 Herzogenrath, Germany. dahmen@cynora.de