1-Silyl-1-boryl-2-alkenes: Reagents for Stereodivergent Allylation Leading to 4-Oxy-(E)-1-alkenylboronates and 4-Oxy-(Z)-1-alkenylsilanes
摘要:
Silylboryl reagents for organic synthesis: 1-silyl-1-boryl-2-alkenes (2) were prepared efficiently by gem-silylborylation of α-chloroallyllithium compounds from (dimethylphenylsilyl)(pinacolato)borane (1; see scheme, LDA=lithium diisopropylamide) and were demonstrated to allylate acetals and aldehydes in the presence of a Lewis acid to produce (E)-4-alkoxy-alkenylboronates. Heating the reagents with aldehydes in the absence of Lewis acid afforded (Z)-4-hydroxy-alkenylsilanes stereospecifically.
Kinetic Resolution of α‐Silyl‐Substituted Allylboronate Esters via Chemo‐ and Stereoselective Allylboration of Aldehydes
作者:Jinyoung Park、Yongsuk Jung、Jeongho Kim、Eunsung Lee、Sarah Yunmi Lee、Seung Hwan Cho
DOI:10.1002/adsc.202001170
日期:2021.4.27
We describe the kinetic resolution of α‐silyl‐substituted allylboronate esters via chiral phosphoric acid‐catalyzed chemo‐, diastereo‐ and enantioselective allylboration of aldehydes. This process provides two synthetically versatile enantioenriched compounds, (Z)‐δ‐silyl‐substituted anti‐homoallylic alcohols and α‐silyl‐substituted allylboronate esters, with a selectivity factor up to 328. We propose
Additions of functionalized α-substituted allylboronates to aldehydes under the novel Lewis and Brønsted acid catalyzed manifolds
作者:Lisa Carosi、Hugo Lachance、Dennis G. Hall
DOI:10.1016/j.tetlet.2005.10.115
日期:2005.12
stereo- and chemoselectivity in the additions of four model α-substituted allylboronates to benzaldehyde was examined under the standard thermal (uncatalyzed) conditions and the novel Lewis and Brønsted acid-catalyzed conditions. With either of Sc(OTf)3 or triflic acid as catalysts, an α-ethyl allylboronate, 1a, led to a surprising inversion of stereoselectivity that can be tentatively rationalized through
Iridium‐Catalyzed Chemo‐, Diastereo‐, and Enantioselective Allyl‐Allyl Coupling: Accessing All Four Stereoisomers of (
<i>E</i>
)‐1‐Boryl‐Substituted 1,5‐Dienes by Chirality Pairing
We report an iridium-catalyzed highly chemo-, diastereo-, and enantioselective allyl-allylcoupling between branched allyl alcohols and α-silyl-substituted allylboronate esters resulting in enantioenriched (E)-1-boryl-substituted 1,5-dienes. All four stereoisomers with two adjacent chiral centers were obtained by chirality pairing. Mechanistic studies were conducted to understand the high levels of
Synthesis of Optically Active Boron–Silicon Bifunctional Cyclopropane Derivatives through Enantioselective Copper(I)‐Catalyzed Reaction of Allylic Carbonates with a Diboron Derivative