Borane-Catalyzed, Chemoselective Reduction and Hydrofunctionalization of Enones Enabled by B–O Transborylation
作者:Kieran Nicholson、Thomas Langer、Stephen P. Thomas
DOI:10.1021/acs.orglett.1c00446
日期:2021.4.2
The use of stoichiometric organoborane reductants in organic synthesis is well established. Here these reagents have been rendered catalytic through an isodesmic B–O/B–H transborylation applied in the borane-catalyzed, chemoselectivealkenereduction and formal hydrofunctionalization of enones. The reaction was found to proceed by a 1,4-hydroboration of the enone and B–O/B–H transborylation with HBpin
A catalytic amount of In(OAc) 3 smoothly promoted 1,4-reduction of certain α-enones with PhSiH 3 in ethanol at ambient temperature. The intermediary enolates could be used for inter- and intramolecular aldol reactions andintramolecular Michael addition.
Access to P-Stereogenic Phosphinates via N-Heterocyclic Carbene-Catalyzed Desymmetrization of Bisphenols
作者:Zhijian Huang、Xuan Huang、Baosheng Li、Chengli Mou、Song Yang、Bao-An Song、Yonggui Robin Chi
DOI:10.1021/jacs.6b04624
日期:2016.6.22
remote P-stereogenic centers is disclosed. The catalytic reactions can be performed on gram scales with 1 mol % N-heterocycliccarbene (NHC) catalyst, providing efficient access to enantiomerically enriched P-stereogenic phosphinates. The chiral phosphinates prepared with our method can find widespread applications as asymmetric organic catalysts and ligands.
Two new chiral diphenylphosphine dioxides bearing an original bis(triazolyl) backbone were prepared through a two‐step sequence. The key reactioninvolves a copper‐catalyzed [3+2] cycloaddition/dimerization reaction leading to the formation of five bonds in one chemical step with 100 % atom efficiency. Interestingly, these ligands exhibited good to excellent catalytic activities as chiral Lewis base
kinetic resolution process. Because of the large steric diaryl phosphoryl group, the synthesized axially chiral anilide has a large rotational barrier. As a demonstration, current studied axially chiral ortho-iodine substituted phosphamides could act as efficient chiral hypervalent iodine(III) catalysts for the asymmetric oxidative dearomatization of phenols. Moreover, a speculative model, which can explain