Confinement-Controlled, Either <i>syn</i>- or <i>anti</i>-Selective Catalytic Asymmetric Mukaiyama Aldolizations of Propionaldehyde Enolsilanes
作者:Tynchtyk Amatov、Nobuya Tsuji、Rajat Maji、Lucas Schreyer、Hui Zhou、Markus Leutzsch、Benjamin List
DOI:10.1021/jacs.1c07447
日期:2021.9.15
Protected aldols (i.e., true aldols derived from aldehydes) with either syn- or anti- stereochemistry are versatile intermediates in many oligopropionate syntheses. Traditional stereoselectiveapproaches to such aldols typically require several nonstrategic operations. Here we report two highly enantioselective and diastereoselective catalytic Mukaiyama aldol reactions of the TBS- or TES- enolsilanes
具有顺式或反式立体化学的受保护醛醇(即来自醛的真正醛醇)是许多低聚丙酸酯合成中的通用中间体。这种醛醇的传统立体选择性方法通常需要几个非战略性操作。在这里,我们报告了丙醛的 TBS-或 TES-烯醇硅烷与芳香醛的两种高度对映选择性和非对映选择性催化 Mukaiyama 羟醛反应。我们的反应以催化剂控制的方式直接提供有价值的甲硅烷基保护的丙醛醛醇,无论是合成还是反异构体。我们已经确定了一种特权 IDPi 催化剂基序,该基序专为控制这些醛醇化反应而设计,具有出色的选择性。我们展示了 IDPi 催化剂内核中的单原子修饰,用CF 2 H 基团替换 CF 3基团,如何导致醛的对映面分化发生戏剧性的转变。这种显着效果的起源归因于通过 CF 2 H 基团的非常规 C-H 氢键使催化腔变紧。
Catalytic Asymmetric Spirocyclizing Diels–Alder Reactions of Enones: Stereoselective Total and Formal Syntheses of α-Chamigrene, β-Chamigrene, Laurencenone C, Colletoic Acid, and Omphalic Acid
作者:Santanu Ghosh、Johannes Eike Erchinger、Rajat Maji、Benjamin List
DOI:10.1021/jacs.2c01971
日期:2022.4.20
We disclose a general catalytic enantioselective Diels–Alderreaction of exo-enones with dienes to give spirocyclanes. The obtained products feature highly congested quaternary stereogenic spirocenters and are used in concise total and formal syntheses of several sesquiterpenes, including of α-chamigrene, β-chamigrene, laurencenone C, colletoic acid, and omphalic acid. The stereo- and regioselectivities