Asymmetric Olefin Isomerization of Butenolides via Proton Transfer Catalysis by an Organic Molecule
作者:Yongwei Wu、Ravi P. Singh、Li Deng
DOI:10.1021/ja205674x
日期:2011.8.17
general olefin isomerization was realized via biomimetic protontransfer catalysis with a new chiral organic catalyst. A broad range of mono- and disubstituted β,γ-unsaturated butenolides were transformed into the corresponding chiral α,β-unsaturated butenolides in high enantioselectivity and yield in the presence of as low as 0.5 mol % catalyst. Mechanistic studies have revealed the protonation as the
Catalytic asymmetric formal γ-allylation of deconjugated butenolides
作者:Amit K. Simlandy、Santanu Mukherjee
DOI:10.1039/c5ob02362a
日期:——
A formal γ-allylation of deconjugatedbutenolides is reported based on a two-step sequence consisting of a catalytic diastereo- and enantioselective vinylogous nucleophilic addition to vinyl sulfones and Julia–Kocienski olefination. This highly modular approach delivers densely functionalized butenolides containing a quaternarystereogenic centre in excellent yield with high enantioselectivity.
Zn-ProPhenol Catalyzed Enantio- and Diastereoselective Direct Vinylogous Mannich Reactions between α,β- and β,γ-Butenolides and Aldimines
作者:Barry M. Trost、Elumalai Gnanamani、Jacob S. Tracy、Christopher A. Kalnmals
DOI:10.1021/jacs.7b11361
日期:2017.12.20
We report a Zn-ProPhenol catalyzedreaction between butenolides and imines to obtain tetrasubstituted vinylogous Mannich products in good yield and diastereoselectivity with excellent enantioselectivity (97 to >99.5% ee). Notably, both α,β- and β,γ-butenolides can be utilized as nucleophiles in this transformation. The imine partner bears the synthetically versatile N-Cbz group, avoiding the use of
Synergistic Lewis base and anion-binding catalysis for the enantioselective vinylogous addition of deconjugated butenolides to allenoates
作者:Vikas Kumar、Santanu Mukherjee
DOI:10.1039/c3cc46858e
日期:——
An enantioselective vinylogous umpolung addition of deconjugated butenolides to allenoates has been developed for the first time with the help of synergistic combination of an achiral phosphine and a chiral squaramide, and represents the first example of a catalytic enantioselective Cγ–Cγ bond formation between two different carbonyl partners.
two‐step procedure that consists of a catalytic enantioselective vinylogousMichaeladdition of deconjugatedbutenolides to cyclopentene‐1,3‐dione and a base‐mediated decarboxylation. The overall process utilizes deconjugatedbutenolides as the source of the highly substituted vinyl unit. Five‐membered carbocycles containing a remote all‐carbon quaternarystereogeniccenter are obtained in good yields and