Highly Stereoselective Synthesis of<i>Z</i>-Homoallylic Alcohols by Kinetic Resolution of Racemic Secondary Allyl Boronates
作者:Celia A. Incerti-Pradillos、Mikhail A. Kabeshov、Andrei V. Malkov
DOI:10.1002/anie.201300709
日期:2013.5.10
α to Z: Racemic α‐chiral allyl boronates, which are readily synthesized from the respective primary allyl halides, undergo a highly efficient kinetic resolution in a face‐ and Z‐selective allylation of aldehydes catalyzed by the chiral Brønsted acid (R)‐TRIP (see scheme; Epin=tetraethylethylene glycol).
New and Stereoselective Synthesis of 1,4-Disubstituted Buten-4-ols (Homoallylic Alcohol α-Adducts) from the Corresponding γ-Isomers (3,4-Disubstituted Buten-4-ols) via an Acid-Catalyzed Allyl-Transfer Reaction with Aldehydes
from aldehydes via the usual reaction with common allylic metals 1, were converted to the corresponding α-adducts 6 by an acid-catalyzed allyl-transfer reaction. In the allyl-transfer reaction, anti- and syn-γ-adducts 3 gave E- and Z-α-adducts 6, respectively, and the optical purity of the γ-adducts 3 was transferred to the α-adducts 6 with >98%ee. This suggests that the allyl-transfer reaction proceeds
Highly (<i>E</i>)-Selective BF<sub>3</sub>·Et<sub>2</sub>O-Promoted Allylboration of Chiral Nonracemic α-Substituted Allylboronates and Analysis of the Origin of Stereocontrol
作者:Ming Chen、William R. Roush
DOI:10.1021/ol1007444
日期:2010.6.18
delta-Methyl-substituted homoallylic alcohols 2 were prepared in 71-88% yield, E:Z>30:1 and 93% to >95% ee via BF3 center dot Et2O-promoted allylboration with alpha-Me-allylboronate 1. The origin of high (E)-selectivity is proposed.
An Unusual Approach to the Synthesis of Enantiomerically Cis Linear Homoallylic Alcohols Based on the Steric Interaction Mechanism of Camphor Scaffold
作者:Chi-Lik Ken Lee、Cheng-Hsia Angeline Lee、Kui-Thong Tan、Teck-Peng Loh
DOI:10.1021/ol049633z
日期:2004.4.1
Camphor is used as the chiral auxiliary for the enantioselective synthesis of cis linear homoallylic alcohols. A range of catalysts, aldehydes, and solvents were investigated to obtain the optimum yield, enantioselectivity, and cis olefinic geometry.
A Novel Enantioselective (2<i>Z</i>)-Alk-2-enylation of Aldehydes via an Allyl-Transfer Reaction from Chiral Allyl Donors Prepared from (+)-Isomenthone
作者:Junzo Nokami、Kenta Nomiyama、Siddiqi M. Shafi、Kazuhide Kataoka
DOI:10.1021/ol0400140
日期:2004.4.1
A highlyenantioselective (2Z)-alk-2-enylation of aldehydes was successfully achieved by an allyl-transferreaction from a chiral allyl donor, which was easily obtained by separation of a diastereomeric mixture of the corresponding homoallylic alcohol gamma-adducts derived from (+)-isomenthone with alk-2-enylmagnesium chloride. [reaction: see text]