Catalytic Conjugate Additions of Carbonyl Anions under Neutral Aqueous Conditions
作者:Michael C. Myers、Ashwin R. Bharadwaj、Benjamin C. Milgram、Karl A. Scheidt
DOI:10.1021/ja0520161
日期:2005.10.1
The conjugateaddition of carbonylanions catalyzed by thiazolium salts that is fully operative under neutral aqueous conditions has been accomplished. The combination of alpha-keto carboxylates and thiazolium-derived zwitterions produces reactive carbonylanions in a buffered protic environment that readily undergo conjugateadditions to substituted alpha,beta-unsaturated 2-acyl imidazoles. The scope
Diastereoselective Trapping of Transient Carboxylic Oxonium Ylides with α,β‐Unsaturated 2‐Acyl Imidazoles
作者:Mengchu Zhang、Tianyuan Zhang、Dan Zhang、Wenhao Hu
DOI:10.1002/adsc.202000701
日期:2020.11.4
By developing a diastereoselective reaction of cyclopropene carboxylic acids with α,β‐unsaturated 2‐acylimidazoles, we reported here a Michael‐type trapping of transient carboxylic oxonium ylides. This transformation provides a direct approach for the construction of valuable γ‐butenolide derivatives in good yields (60–99%) with high diastereoselectivities (up to >95:5 dr) under mild reaction conditions
Asymmetric Umpolung (3+2) Cycloadditions of Iminoesters with α,β-Unsaturated-2-acyl Imidazoles for the Synthesis of Substituted Pyrrolidines
作者:Mamta Gill、Arko Das、Vinod K. Singh
DOI:10.1021/acs.orglett.2c01438
日期:2022.8.12
enantioselective (3+2) cycloaddition reaction of iminoesters occurring with opposite regioselectivity is reported. This reaction provides chiral polysubstituted pyrrolidines with high enantioselectivities (up to 97%), diastereoselectivities (>20:1), and yields (up to 99%). Interestingly, changing the alpha-substituents of the iminoesters from an aryl to an aliphatic (benzyl) group or hydrogen resulted
Enantioselective synthesis of substituted 1-pyrrolines via Michael addition of iminoesters with α,β-unsaturated 2-acyl imidazoles catalyzed by chiral Cu(I)-BPE complex
作者:Mamta Gill、Vinod K. Singh
DOI:10.1016/j.tetlet.2023.154555
日期:2023.6
A highly chemo-, diastereo-, and enantioselective Cu(I)-1,2-Bis((2S,5S)-2,5-diphenylphospholano)ethane (BPE) catalyzed Michael addition of iminoesters to α, β-unsaturated 2-acyl imidazoles at 0 °C and subsequent silica-assisted cyclization of Michael adducts into highly functionalized 1-pyrrolines bearing two contiguous stereocenters (up to >20: 1 cr, > 20: 1 dr, and 99% ee) has been described.
一种高度化学、非对映和对映选择性的 Cu(I)-1,2-双((2 S ,5 S )-2,5-二苯基膦基)乙烷 (BPE) 催化亚氨基酯迈克尔加成到α , β -不饱和0 °C 下的2-酰基咪唑和随后的二氧化硅辅助迈克尔加合物环化成带有两个连续立体中心的高度功能化的 1-吡咯啉(高达 >20: 1 cr,> 20: 1 dr,和 99% ee)已被描述.
A General Strategy for the Synthesis of Truxinate Natural Products Enabled by Enantioselective [2+2] Photocycloadditions
作者:Matthew J. Genzink、Matthew D. Rossler、Herman Recendiz、Tehshik P. Yoon
DOI:10.1021/jacs.3c07132
日期:2023.9.6
Pseudodimeric cyclobutanes constitute a large class of natural products that could, in principle, be efficiently synthesized via [2+2] photocycloadditions. However, the difficulty in developing chemo-, regio-, diastereo-, and enantioselective cycloadditions has limited their use in asymmetric syntheses. Herein, we show that chiral acid catalysts promote highly selective visible-light photocycloadditions