Direct Catalytic Asymmetric Vinylogous Additions of α,β‐ and β,γ‐Butenolides to Polyfluorinated Alkynyl Ketimines
作者:Barry M. Trost、Chao‐I. (Joey) Hung、Manuel J. Scharf
DOI:10.1002/anie.201806249
日期:2018.8.27
We report a Zn‐ProPhenol catalyzed asymmetric Mannich reaction between butenolides and polyfluorinated alkynyl ketimines to obtain vinylogous products featuring two contiguous tetrasubstituted stereogenic centers. Notably, this is the first successful use of ketimines in the ProPhenol Mannich process, and the reaction offers a new approach for the preparation of pharmaceutically relevant products possessing
Domino Ring-Closing Metathesis/Intramolecular Transfer of an Alkenyl Subunit: A Direct Formation of Functionalized Butenolides and Pyrones from α,β- and β,γ-Unsaturated Esters
作者:Olivier Piva、Marie-Alice Virolleaud
DOI:10.1055/s-2004-831329
日期:——
A direct synthesis of butenolides and β,γ-unsaturated δ-lactones has been devised by combining a ring-closing metathesis (RCM) with a cross-coupling metathesis (CM) process. The first step of the reaction generates a new carbene group, which is able to functionalize the lateral unsaturated chain during the second coupling reaction. In this way, the transfer of the alkyl group R, initially fixed on the acid chain, avoids the use of an alkene partner introduced in large excess.
通过将闭环偏合成(RCM)与交叉偶联偏合成(CM)工艺相结合,设计出了一种丁烯内酯和δ,δ-不饱和δ-内酯的直接合成方法。反应的第一步产生了一个新的碳烯基,在第二步偶联反应中,该碳烯基能够使侧向不饱和链官能化。这样,最初固定在酸链上的烷基 R 的转移就避免了使用大量过量引入的烯伴侣。
NHC–Cu(i) catalysed asymmetric conjugate silyl transfer to unsaturated lactones: application in kinetic resolution
作者:Vittorio Pace、James P. Rae、Hassan Y. Harb、David J. Procter
DOI:10.1039/c3cc42160k
日期:——
The scope of the asymmetric silyl transfer to unsaturated lactones utilising a C2-symmetric NHCâCu(I) catalyst has been established and kinetic resolutions mediated by silyl transfer have been used to prepare enantiomerically enriched anti-4,5-disubstituted 5-membered lactones. The method has been exploited in an expedient synthesis of (+)-blastmycinone.
Direct Enantio- and Diastereoselective Vinylogous Addition of Butenolides to Chromones Catalyzed by Zn-ProPhenol
作者:Barry M. Trost、Elumalai Gnanamani、Christopher A. Kalnmals、Chao-I “Joey” Hung、Jacob S. Tracy
DOI:10.1021/jacs.8b13367
日期:2019.1.30
We report the first enantio- and diastereoselective 1,4-addition of butenolides to chromones. Both α,β- and β,γ-butenolide nucleophiles are compatible with the Zn-ProPhenol catalyst, and preactivation as the siloxyfurans is not required. The scope of electrophiles includes a variety of substituted chromones, as well as a thiochromone and a quinolone, and the resulting vinylogous addition products are
Diastereoselective addition of nitro compounds to α,β-unsaturated γ-butyrolactones
作者:Giovanni B. Rosso、Ronaldo A. Pilli
DOI:10.1016/j.tetlet.2005.10.163
日期:2006.1
Herein, we report our results on the diastereoselective addition of nitrocompounds to α,β-unsaturated γ-butyrolactones, which afforded the corresponding Michael adducts 9–17 in moderate to good yields and good to excellent diastereoisomeric ratio. A one-pot conversion of α,β-unsaturated γ-butyrolactones 7 and 8 to the corresponding trisubstituted keto-γ-butyrolactones 24 and 25 via a tandem Michael–Nef