Phosphine-Catalyzed [4 + 1] Annulation between α,β-Unsaturated Imines and Allylic Carbonates: Synthesis of 2-Pyrrolines
作者:Junjun Tian、Rong Zhou、Haiyun Sun、Haibin Song、Zhengjie He
DOI:10.1021/jo200164v
日期:2011.4.1
In this report, a phosphine-catalyzed [4 + 1] annulationbetween α,β-unsaturated imines and allylic carbonates is described. This reaction represents the first realization of catalytic [4 + 1] cyclization of 1,3-azadienes with in situ formed phosphorusylides, which provides highly efficient and diastereoselective synthesis of 2-pyrrolines.
Copper-catalyzed conjugate protosilylation reaction of α,β-unsaturated sulfonyl ketimines has been developed. The corresponding E- and Z-stereoselective functionalized allylsilane products were obtained in good yields respectively via tuning the ligands used in the reactions. Furthermore, the highly enantioselective (E)-β-tosylamine-substituted allylsilanes were also achieved in the presence of chiral
DMAP-promoted in situ activation of bromoacetic acid as a 2-carbon synthon for facile synthesis of pyridines and fused pyridin-2-ones
作者:Lu Wang、Gaoyuan Zhu、Weifang Tang、Tao Lu、Ding Du
DOI:10.1016/j.tet.2016.08.062
日期:2016.10
A general and simple synthesis of 2,4,6-trisubstituted pyridines and fused pyridine-2-ones from bromoacetic acid is developed via a DMAP-promoted in situ activation strategy. In this protocol, readily accessible bromoacetic acid has been effectively employed as a 2C synthon to undergo formal [2+4] cycloadditions with diverse acyclic and cyclic 1-azadienes. Low costs of the reagents and materials, mild
Asymmetric Access to the Smallest Enolate Intermediate via Organocatalytic Activation of Acetic Ester
作者:Shaojin Chen、Lin Hao、Yuexia Zhang、Bhoopendra Tiwari、Yonggui Robin Chi
DOI:10.1021/ol402877n
日期:2013.11.15
An NHC-catalyzed activation of acetic esters to afford enolate intermediates is disclosed. The catalytically generated triazolium enolate intermediates serve as two-carbon nucleophiles that undergo highly enantioselective reactions with enones and alpha,beta-unsaturated imines to give a-unsubstituted delta-lactones and lactams, respectively.