of racemic β-halo-α-keto esters through carbonyl-enereaction were realized using a chiral N,N′-dioxide-nickel(II) complex, giving the corresponding β-halo-α-hydroxy esters containing two vicinal chiral tri- and tetrasubstituted carbon centers in good yields and dr with excellent ee values without the use of extra bases. Meanwhile, a proposed reactionmechanism was presented according to the configuration
Dynamic Kinetic Asymmetric Cross-Benzoin Additions of β-Stereogenic α-Keto Esters
作者:C. Guy Goodman、Jeffrey S. Johnson
DOI:10.1021/ja508521a
日期:2014.10.22
The dynamickineticresolution of β-halo α-keto esters via an asymmetric cross-benzoin reaction is described. A chiral N-heterocycliccarbenecatalyzes the umpolung addition of aldehydes to racemic α-keto esters. The resulting fully substituted β-halo glycolic ester products are obtained with high levels of enantio- and diastereocontrol. The high chemoselectivity observed is a result of greater electrophilicity