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.
AbstractWe report a triple vinylogous cascade reaction, yielding valuable spiro‐oxindolic cyclohexane derivatives. The three‐component domino process proceeds by way of a catalyzed Michael/1,6‐addition/vinylogous aldol sequence affording the products with six stereogenic centers and very high control over the stereochemistry. The chemistry is based on a rare example of asymmetric 1,6‐addition to linear 2,4‐dienals proceeding with complete δ‐site selectivity. Key to the reaction development was a directing group positioned at the β‐dienal position, which was essential for achieving highly predictable reaction outcomes.magnified image
Copper and Rhodium Relay Catalysis for Selective Access to <i>cis</i>-2,3-Dihydroazepines
作者:You Li、Han Luo、Zongyuan Tang、Yingzi Li、Luan Du、Xiaolan Xin、Shanshan Li、Baosheng Li
DOI:10.1021/acs.orglett.1c02262
日期:2021.8.20
access synthetically challenging cis-2,3-dihydroazepines is reported. The reaction starts with readily available dienals, alkynes, and sulfonyl azides as the substrates and employs copper and rhodium as relay catalysts. Key steps include a copper-catalyzed reaction between an alkyne and a sulfonyl azide to form a triazole intermediate. The subsequent activation of this triazole intermediate by a rhodium
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