Improved Cr-Catalyzed Enantioselective Allylation of Aldehydes

Significance

The authors’ aim was to develop a scalable method for allylation which would allow recovery of the chiral ligand. The described procedure improved the practicality of a reaction they developed earlier (J. Am. Chem. Soc. 2004, 126, 12248). Under the above conditions, the 2-iodoallylation reaction gave B on a 30 g scale, and ligand A was recovered in 83% yield (X = I). It is noteworthy that the catalytic allylation reaction affords exceptional selectivity in cases where the aldehyde is already chiral (D and E; with matched ligand).