Regio- and Diastereoselective Ene Reaction of 4-Phenyl-1,2,4-triazoline-3,5-dione with Chiral Allylic Alcohols and Their Derivatives
摘要:
Chiral allylic alcohols la-e reacted with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) in CH2Cl2 to produce 3-amino-1-alken-4-ols 2 and 3 in 78-89% yields, with 68-90% diastereomeric excess (de) in favor of the three isomer. Chiral allylic ethers If,g and acetates Ih,i gave similar yields but lower de (34-66%). Reaction of allylic alcohols 6a-e with PTAD in CH2Cl2 produced 1,3-regioisomers 7 and 8 exclusively in 33-65% yields without apparent diastereoselectivity, except when R-1 was a Bu-t group, in which case only syn product 7 was formed. However, when 6a or 6c was subjected to reaction with PTAD in a polar solvent, up to 88% de was observed. Reaction of allylic ethers 6f,g and acetates 6h,i with PTAD in CH2Cl2 also produced 7 and 8 exclusively with improved yields (56-96%) and diastereoselectivity (50-100% de in favor of the syn isomer).
Enantioselective C−C Bond Formation by Rhodium-Catalyzed Tandem Ylide Formation/[2,3]-Sigmatropic Rearrangement between Donor/Acceptor Carbenoids and Allylic Alcohols
作者:Zhanjie Li、Huw M. L. Davies
DOI:10.1021/ja9075293
日期:2010.1.13
The rhodium-catalyzed reaction of racemic allyl alcohols with methyl phenyldiazoacetate or methyl styryldiazoacetate results in a two-step process, an initial oxonium ylide formation followed by a [2,3]-sigmatropic rearrangement. This process competes favorably with the more conventional O-H insertion chemistry as long as donor/acceptor carbenoids and highly substituted allyl alcohols are used as substrates
Kinetic resolution of racemic allylic alcohols <i>via</i> iridium-catalyzed asymmetric hydrogenation: scope, synthetic applications and insight into the origin of selectivity
作者:Haibo Wu、Cristiana Margarita、Jira Jongcharoenkamol、Mark D. Nolan、Thishana Singh、Pher G. Andersson
DOI:10.1039/d0sc05276k
日期:——
Asymmetric hydrogenation is one of the most commonly used tools in organic synthesis, whereas, kineticresolution via asymmetric hydrogenation is less developed. Herein, we describe the first iridium catalyzed kineticresolution of a wide range of trisubstituted secondary and tertiary allylic alcohols. Large selectivity factors were observed in most cases (s up to 211), providing the unreacted starting
不对称氢化是有机合成中最常用的工具之一,而通过不对称氢化进行动力学拆分的开发较少。在此,我们描述了各种三取代仲和叔烯丙醇的第一次铱催化动力学拆分。在大多数情况下观察到较大的选择性因子(高达211),从而以良好的收率和高水平的对映体纯度(ee 高达 >99%)提供未反应的起始材料。该方法的实用性在一些生物活性天然产物的对映选择性正式合成中得到了强调,包括 pumiliotoxin A、inthomycin A 和 B。提出了 DFT 研究和关于选择性起源的选择性模型。
Hydroxy-Directed Regio- and Diastereoselective [2+2] Photocycloaddition (Paternò−Büchi Reaction) of Benzophenone to Chiral Allylic Alcohols
作者:Waldemar Adam、Karl Peters、Eva Maria Peters、Veit R. Stegmann