One-Pot Reactions for Modular Synthesis of Polysubstituted and Fused Pyridines
作者:Zhidong Song、Xin Huang、Wenbin Yi、Wei Zhang
DOI:10.1021/acs.orglett.6b02883
日期:2016.11.4
3-dicarbonyl-initiated one-pot Michael addition/[5 + 1] annulation/dehydrofluorinative aromatization reaction sequence is introduced for regioselectivesynthesis of di-, tri-, tetra-, and pentasubstituted pyridines as well as fusedpyridines. This simple and modular synthesis is performed using readily available starting materials and under transition-metal catalyst-free conditions.
Recyclable Organocatalysts for a One-Pot Asymmetric Synthesis of 2-Fluorocyclohexanols Bearing Six Contiguous Stereocenters
作者:Xin Huang、Miao Liu、Jerry P. Jasinski、Bo Peng、Wei Zhang
DOI:10.1002/adsc.201700129
日期:2017.6.6
A recyclable fluorous bifunctional Cinchona alkaloid/thiourea‐catalyzed quadruple fluorination/Michael/Michael/aldol sequence has been developed for the one‐pot synthesis of cyclohexanols bearing six contiguous stereocenters including a fluorinated tertiary carbon. By using readily available starting materials including β‐keto esters, β‐nitrostyrenes, and α,β‐unsaturated aldehydes, fully functionalized
已开发出可回收的氟双功能金鸡纳生物碱/硫脲催化的四重氟化/ Michael / Michael / aldol序列,用于一锅合成带有六个连续立体中心(包括氟化叔碳)的环己醇。通过使用容易获得的原料,包括β-酮酸酯,β-硝基苯乙烯和α,β-不饱和醛,可以以52-80%的产率合成全功能化的环己醇,ee高达99%,dr > 20:1。氟固相萃取可以很容易地回收含氟催化剂,产率为94-97%,纯度> 98%。除了通过罐式经济反应实现高合成效率外,还采用了其他绿色技术,例如无过渡金属催化和催化剂回收。
Primary-secondary diamines catalyzed Michael reaction to generate chiral fluorinated quaternary carbon centers
作者:Yingpeng Lu、Gang Zou、Gang Zhao
DOI:10.1016/j.tet.2015.04.103
日期:2015.6
Asymmetric Michaelreactions of α-fluoro-β-ketoesters to nitroolefins have been achieved by using readily accessible primary-secondary diamines as the organocatalysts through enamine activation mode, affording the useful Michael adducts bearing chiral fluorinated quaternary carbon in good yields, with high diastereoselectivities and enantioselectivities (up to 87% yield, >20:1 d.r. and 99% ee).
Intramolecular Cyclization Manifolds of 4-Alkylpyridines Bearing Ambiphilic Side Chains: Construction of Spirodihydropyridines or Benzylic Cyclization via Anhydrobase Intermediates
作者:Sharavathi G. Parameswarappa、F. Christopher Pigge
DOI:10.1021/jo301247c
日期:2012.9.21
side chains have been converted to spirodihydropyridines upon treatment with ethyl chloroformate and sub-stoichiometric amounts of Ti(OiPr)4. Alternatively, inclusion of mild base in the reaction medium was found to facilitate generation of anhydrobase intermediates. Subsequent aldol-like condensations with electrophilic side chain moieties followed by hydrolysis delivered benzylically cyclized pyridines
在用氯甲酸乙酯和亚化学计量的Ti(O i Pr)4处理后,具有亲核β-二羰基侧链的4-烷基吡啶已转化为螺二氢吡啶。或者,发现在反应介质中包含温和的碱有助于促进脱水碱中间体的产生。随后与亲电子侧链部分的醛醇状缩合,然后水解,以高收率递送苄基环化的吡啶。环化脱水碱中间体的原位氢化得到4-取代的哌啶。