Accessing Both Retention and Inversion Pathways in Stereospecific, Nickel-Catalyzed Miyaura Borylations of Allylic Pivalates
作者:Qi Zhou、Harathi D. Srinivas、Songnan Zhang、Mary P. Watson
DOI:10.1021/jacs.6b07396
日期:2016.9.14
enable access to eitherenantiomer of allylboronate product from a single enantiomer of readily prepared allylic pivalate substrate. Excellent functional group tolerance, yields, regioselectivities, and stereochemical fidelities are observed. The stereochemical switch from stereoretention to stereoinversion largely depends upon solvent and can be explained by competitive pathways for the oxidative
A Novel Tandem Michael Addition/Meerwein−Ponndorf−Verley Reduction: Asymmetric Reduction of Acyclic α,β-Unsaturated Ketones Using A Chiral Mercapto Alcohol
The introduction of a thiol group into a chiral alcohol reagent for asymmetric Meerwein−Ponndorf−Verley (MPV) reductions allows asymmetric reduction of α,β-unsaturated ketones to secondary alcohols and allylic alcohols via a novel tandem Michael addition/MPV reduction. The reaction of acyclic α,β-unsaturated ketones 1 and an optically active 1,3-mercapto alcohol (−)-2 using dimethylaluminum chloride
An efficient method for Pd-catalyzed stereospecific allyl-aryl coupling of allylic alcohols with arylboronicacids has been described. The reactions proceeded smoothly in the presence of Pd2(dba)3.CHCl3 and racemic BINAP under mild and neutral conditions, affording allyl-aryl coupling products in moderate to high yields with excellent stereospecificities.
Enantioselective addition of tris(TADDOL) organocerium reagents to aldehydes
作者:Nicholas Greeves、J.Elizabeth Pease
DOI:10.1016/0040-4039(96)01236-1
日期:1996.8
A significant improvement in enantioselectivity (up to 92% ee) was achieved in butyl additions to a range of aldehydes with a novel tris(TADDOL) organoceriumreagent.
Room temperature and highly enantioselective additions of alkyltitanium reagents to aldehydes catalyzed by a titanium catalyst of (R)-h8-binol
作者:Qinghan Li、Han-Mou Gau
DOI:10.1002/chir.21018
日期:2011.11
n‐butyl as compared with the enantioselectivities of products from the addition reactions of the branched i‐butyl group. The same stereochemistry of RTi(O‐i‐Pr)3 addition reactions as the addition reactions of organozinc, organoaluminum, Grignard, or organolithium reagents directly supports the argument of that titanium‐catalyzed addition reactions of aldehydes involve an addition of an organotitanium nucleophile