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
this article is a palladium(II)/copper(II)‐ or palladium(II)‐catalyzed intermolecular cyclization of acrylic acid with alkenes to produce α‐methylene‐γ‐butyrolactone derivatives using molecular oxygen as an environmentally benign oxidant. In this system, the carboxylato, especially trifluoroacetato, or trimethylacetato ligand, plays a quite important role to afford a high catalytic activity by suppressing
Gold-Catalyzed Cascade Cyclization−Oxidative Alkynylation of Allenoates
作者:Matthew N. Hopkinson、Jonathan E. Ross、Guy T. Giuffredi、Antony D. Gee、Véronique Gouverneur
DOI:10.1021/ol102061k
日期:2010.11.5
A gold(I)-catalyzed cascade cyclization−oxidative cross-coupling process has been applied to prepare β-alkynyl-γ-butenolides directly from allenoates and various terminal alkynes. Following an initial gold-catalyzed C−O bond forming allenoatecyclization, a mechanism based on a AuI/AuIII redox cycle has been proposed with Selectfluor acting as the external oxidant.
金(I)催化的级联环化-氧化交叉偶联工艺已被用于直接从脲基酸酯和各种末端炔烃制备β-炔基-γ-丁烯内酯。在最初的金催化的C-O键形成脲酸酯环化之后,已经提出了一种基于Au I / Au III氧化还原循环的机理,其中Selectfluor用作外部氧化剂。
Chiral Betaine-Mediated Efficient Organocatalytic Asymmetric Isomerization of β,γ-Unsaturated Butenolides
An asymmetric isomerization of β,γ-unsaturated butenolides with a newly developed betaine catalyst at a 0.2–2 mol% loading, an improvement upon available methods that use 0.5–2.0 mol% catalyst.
Synthesis of 2-(5H)-furanones by cyclization of alkyl allene carboxylates in triflic acid
作者:Oussama Abdelhamid Mammeri、Ilia M. Baranov、Alexandr Yu Ivanov、Irina A. Boyarskaya、Aleksander V. Vasilyev
DOI:10.1016/j.tet.2023.133649
日期:2023.10
(triflic acid, TfOH) at room temperature or 70 °C for 30 min are cyclized to form 2-(5H)-furanones in yields up to 83%. The reaction cationic intermediates, O-monoprotonated [R2(R3)C=C=C(R1)–C(=O+H)OAlk] and O,C-diprotonated [R2(R3)C+–CH=C(R1)–C(=O+H)OAlk] forms of starting allenes, have been studied experimentally by NMR and theoretically by DFT calculations. It has been found that the cyclization proceeds