Commercially available neat organozincs as highly reactive reagents for catalytic enantioselective addition to ketones and aldehydes under solvent free conditions
作者:Manabu Hatano、Tomokazu Mizuno、Kazuaki Ishihara
DOI:10.1016/j.tet.2011.02.042
日期:2011.6
Ph2Zn, and highly concentrated Me2Zn are highly reactive organozinc reagents, which are commercially available in bulk quantities. We here report a catalytic enantioselective Et2Zn, Ph2Zn, and Me2Zn addition to ketones and aldehydes under solventfree or highly concentrated conditions without Ti(Oi-Pr)4 as a conventional activator of organozinc reagents. The desired optically active tertiary and secondary
A practical and useful, catalyticenantioselective method has been developed for the synthesis of tertiary diaryl and aryl heteroaryl carbinols starting from commercially available aromatic ketones and aryl or heteroaryl bromides. In this method, organotitanium reagents are generated in situ from the bromides by lithiation with nBuLi followed by transmetallation of the resulting organolithiums with
已经开发了一种实用且有用的催化对映选择性方法,用于从可商购的芳族酮和芳基或杂芳基溴化物开始合成叔二芳基和芳基杂芳基甲醇。在该方法中,通过用n BuLi锂化从溴化物中原位生成有机钛试剂,然后用ClTi(O i Pr)3对所得的有机锂进行金属转移。在(R)-3-(3,5-双三氟甲基苯基)-1,1'-联-2-萘酚(BTFP-BINOL)以高对映选择性和高收率提供了相应的叔醇。反应也可以从呋喃和2-噻吩基锂开始。该方法操作简单,可在10 mmol规模下进行而没有任何困难。
Zn(salen)-Catalyzed Enantioselective Phenyl Transfer to Aldehydes and Ketones with Organozinc Reagent
A chiral zinc complex of salen was found to be an efficient catalyst for the phenyl transfer of organozinc reagent to aromaticaldehydes and ketones. High enantioselectivities were obtained in reactions of both aromaticaldehydes and ketones (up to 97% and 92% ee, respectively).
A highly efficient enantioselective organozinc (R2Zn) addition to ketones catalyzed by chiral phosphoramide-Zn(II) complexes (1-10 mol %) has been developed. These complexes serve as conjugate Lewis acid-Lewis base catalysts. Chiral phosphoramides are derived from an inexpensive natural amino acid (i.e., L-valine). From a variety of nonactivated aromatic and aliphatic ketones, the corresponding optically
Enantioconvergent Arylation of Racemic Secondary Alcohols to Chiral Tertiary Alcohols Enabled by Nickel/N-Heterocyclic Carbene Catalysis
作者:Yuan Cai、Shi-Liang Shi
DOI:10.1021/jacs.1c06614
日期:2021.8.11
available achiral alcohols via C–H functionalization is an ideal strategy to prepare value-added chiral higher alcohols. Herein, we disclose the first enantioconvergent upgrading reaction of simple racemic secondary alcohols to enantioenriched tertiaryalcohols. An N-heterocycliccarbene (NHC)-nickel catalyst was leveraged to enable this highly efficient formal asymmetric alcohol α-C–H arylation via