Catalytic Asymmetric Epoxidation of α-Branched Enals
作者:Olga Lifchits、Corinna M. Reisinger、Benjamin List
DOI:10.1021/ja1037935
日期:2010.8.4
An asymmetric catalytic epoxidation of alpha-branched, alpha,beta-unsaturated aldehydes is presented. A highly synergistic combination of a primary cinchona-based amine and a chiral phosphoric acid was found to promote the reaction with excellent enantiocontrol for alpha-monosubstituted and alpha,beta-disubstituted enals.
Synthesis of the C
<sub>1</sub>
‐C
<sub>10</sub>
Fragment of Muamvatin
作者:Anandaraju Bandaru、Krishna P. Kaliappan
DOI:10.1002/asia.202000459
日期:2020.7.16
This report delineates our efforts towards the synthesis of a stereochemically well‐defined ketone, the C1−C10 fragment of muamvatin, the first example of a 2, 4, 6‐trioxaadamantane ring skeletal polypropionate marine natural product, using two non‐aldol variants. i) The Shimizu reaction, a Pd(0) mediated stereoselective epoxy‐ring opening of alkenyl oxiranes, was employed for the stereoselective installation
Highly Regio- and Enantioselective Monoepoxidation of Conjugated Dienes
作者:Michael Frohn、Molly Dalkiewicz、Yong Tu、Zhi-Xian Wang、Yian Shi
DOI:10.1021/jo9721195
日期:1998.5.1
This paper describes a highly effective and mild asymmetric monoepoxidation method for conjugated dienes using a fructose-derived chiral ketone 1 as catalyst and Oxone as oxidant. The regioselectivies and enantioslectivies are very high in most cases. For unsymmetrical dienes, the regioselectivity can be regulated by using steric and electronic control. The olefin substrates include trans-disubstituted and trisubstituted olefins that can bear a wide range of functional groups such as hydroxyl groups, TBS ethers, or esters. The enantiomeric excesses for the major monoepoxides range from 89% to 97%. The epoxidation is believed to proceed via a spiro mode.