The first catalytic enantioselective 1,2-reduction of enones with 0.45 mol equiv potassium borohydride solution catalyzed by a chiralN,N′-dioxide–Sc(III) complex catalyst was accomplished under mild reaction conditions. A number of optically active allylic alcohols were obtained in good to excellent enantioselectivities (up to 95% ee) with nearly quantitative yields.
Synthesis of Enantioenriched Allylic Silanes via Nickel-Catalyzed Reductive Cross-Coupling
作者:Julie L. Hofstra、Alan H. Cherney、Ciara M. Ordner、Sarah E. Reisman
DOI:10.1021/jacs.7b11707
日期:2018.1.10
asymmetric Ni-catalyzed reductive cross-coupling has been developed to prepare enantioenriched allylic silanes. This enantioselective reductive alkenylation proceeds under mild conditions and exhibits good functional group tolerance. The chiral allylic silanes prepared here undergo a variety of stereospecific transformations, including intramolecular Hosomi-Sakurai reactions, to set vicinal stereogenic centers
已开发出不对称 Ni 催化的还原交叉偶联来制备对映体富集的烯丙基硅烷。这种对映选择性还原烯基化在温和条件下进行,并表现出良好的官能团耐受性。这里制备的手性烯丙基硅烷经过各种立体定向转化,包括分子内细美-樱井反应,以设置具有优异手性转移的邻位立体中心。
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
enantioselective 1,2-reduction of α,β-unsaturated ketones has been achieved using a chiral pincer Mn catalyst. A series of PNN tridentate ligands containing benzimidazole groups were designed with ferrocene as the backbone, which coordinated with Mn to form the active catalyst. This mild process represents a general method to access chiralallyl alcohols with high catalytic activity (up to 9500 TON) and high enantioselectivity
Chiral (R)- and (S)-allylic alcohols with an enantiomeric excess exceeding 99% have been prepared in good to high overall isolated yields through a two-step one-pot chemoenzymatic process based on the palladium-catalyzed Heck reaction of aryl iodides with butenone followed by an enzymatic reduction of the resultant vinylic substitution products. Alcohol dehydrogenases from Lactobacillus brevis and Thermoanaerobacter species were used to attain (R)- and (S)-stereoselectivity, respectively. (c) 2007 Elsevier Ltd. All rights reserved.