A modular approach toward the synthesis of 2,4-disubstituted pyridines
摘要:
A number of 2,4-disubstituted pyridines have been synthesized using alpha,beta,gamma,delta-unsaturated aldehydes and ammonium chloride in the presence of triethylamine in acetonitrile solvent at 80 degrees C under air balloon. (C) 2013 Elsevier Ltd. All rights reserved.
A Study of the Reactions of 3‐Bromopropenals with Anilines for the Synthesis of α‐Bromo Enaminones
作者:Sundaram Suresh、Prakash Bhimrao Patil、Pao‐Hsing Yu、Chia‐Chi Fang、Yin‐Zhi Weng、Veerababurao Kavala、Ching‐Fa Yao
DOI:10.1002/adsc.202100779
日期:2021.11.9
The reactions proceed via the p-toluenesulfonic acid monohydrate (TsOH ⋅ H2O) catalyzed reactions of 3-bromopropenals with anilines in dimethyl sulfoxide (DMSO) and does not require an external brominating agent. The chemoselective 1,2-addition was accomplished by employing aniline with a sterically hindered electron-withdrawing group attached at the ortho-position. In addition, the reactions involving
One-Pot Stereoselective Synthesis of (<i>Z</i>)-β-Ketoenamides from β-Halo α,β-Unsaturated Aldehydes
作者:Junali Gogoi、Pranjal Gogoi、Romesh C. Boruah
DOI:10.1002/ejoc.201400007
日期:2014.6
β-ketoenamides have been synthesized from their corresponding β-halo α,β-unsaturatedaldehydes. This synthetic methodology provides efficient access to (Z)-β-ketoenamides. The structures of these products have been unambiguously established by single crystal XRD studies. This process is found to be mild and inexpensive. The required β-halo α,β-unsaturatedaldehydes are synthesized from corresponding ketones using
Divergent NHC-Catalyzed Oxidative Transformations of 3-Bromoenal: Selective Synthesis of 2<i>H</i>-Pyran-2-ones and Chiral Dihydropyranones
作者:Gang Wang、Xia Chen、Gaohan Miao、Weijun Yao、Cheng Ma
DOI:10.1021/jo400950j
日期:2013.6.21
A selectivesynthesis of either 2H-pyran-2-ones (4) or chiral dihydropyranones (6) from the same substrates of 3-bromoenals and 1,3-dicarbonyl compounds upon oxidative N-heterocyclic carbene catalysis is presented. It is shown that the oxidative transformation of 3-bromoenals under NHC catalyst can be well controlled to proceed through two pathways, i.e., elimination of reducible β-bromide or by an
β-halo α,β-unsaturated aldehydes by a microwave-assisted Knoevenagel reaction. The β-halo-α,β-unsaturated aldehydes were, in turn, efficiently synthesized from the corresponding ketones by a Vilsmeier formylation reaction. The protocol was used to synthesize several novel steroidal and nonsteroidal fused 2-aminopyridine derivatives. 2-Aminopyridines were synthesized from β-halo α,β-unsaturated aldehydes
Atroposelective Arene Formation by Carbene‐Catalyzed Formal [4+2] Cycloaddition
作者:Ke Xu、Wenchang Li、Shaoheng Zhu、Tingshun Zhu
DOI:10.1002/anie.201910049
日期:2019.12.2
Atroposelective arene formation is an efficient method to build axially chiral molecules with multi-substituted arenes. Reported here is an organocatalyzed atroposelective arene formationreaction by an N-heterocyclic carbene (NHC) catalyzed formal [4+2] cycloaddition of conjugated dienals and α-aryl ketones. This study expands the synthetic potential of NHC organocatalysis and provides a competitive