Expeditious synthesis of pyrano[2,3,4-de]quinolines via Rh(<scp>iii</scp>)-catalyzed cascade C–H activation/annulation/lactonization of quinolin-4-ol with alkynes
作者:Gang Liao、Hong Song、Xue-Song Yin、Bing-Feng Shi
DOI:10.1039/c7cc04113f
日期:——
One-step synthesis of tetracyclic pyrano[2,3,4-de]quinolones via Rh(iii)-catalyzed cascade C–H activation/annulation/lactonization is described.
Functionalized Hexahydropyrrolo[2,1‐
<i>b</i>
]oxazoles from Catalyst‐Free Annulation of Δ
<sup>1</sup>
‐Pyrrolines with Electron‐Deficient Propargylic Alcohols
作者:Ludmila A. Oparina、Dmitrii A. Shabalin、Anastasiya G. Mal'kina、Nikita A. Kolyvanov、Lyudmila A. Grishchenko、Igor' A. Ushakov、Alexander V. Vashchenko、Boris A. Trofimov
DOI:10.1002/ejoc.202000582
日期:2020.7.23
Catalyst‐free annulation of Δ1‐pyrrolines with electron‐deficient propargylic alcohols was demonstrated allowing the formation of functionalized hexahydropyrrolo[2,1‐b ]oxazoles in good to excellent yields.
证实了无电子的炔丙基醇对Δ1-吡咯啉的无催化剂环化反应,可以形成官能化的六氢吡咯并[2,1- b ]恶唑,收率高至优异。
A Convenient Entry to 5-(sp<sup>2</sup>)-Substituted and 5,5-Disubstituted Tetronic Acids
作者:Fernando García-Tellado、David Tejedor、Alicia S antos-Expósito
DOI:10.1055/s-2006-941596
日期:2006.6
A one-pot, convenient and general access to 5-sp2-substituted and 5,5-disubstituted tetronic acids is described. The protocol embodies two consecutive chemical events: a Michael addition of pyrrolidine on a secondary or tertiary γ-hydroxy-α,β-alkynyl ester derivative to give the corresponding enamine, and the subsequent acid-catalyzed hydrolysis-lactonization of this intermediate to afford the tetronic acid derivative.
Rhodium‐Catalyzed Regioselective C—O and C—C Bonds Formation of 3‐Oxopent‐4‐enenitriles with Alkynes for the Synthesis of Polysubstituted 2H‐Pyrans
作者:Kelu Yan、Xiao Liu、Jiangwei Wen、Qiuyun Li、Junjie Wang、Yang Zheng、Xiu Wang
DOI:10.1002/cjoc.202400239
日期:2024.9
The rhodium-catalyzedC—Hbondactivation and cyclization of 3-oxopent-4-enenitriles with alkynes proceed efficiently. Various 2H-pyrans with multiple substituents are achieved in good yields through regioselective formation of C—O and C—C bonds. Transformations involving hydroxy-alkynoates resulted in products with a furo[3,4-b]pyran skeleton via further intramolecular ester exchange processes. Different
铑催化的 C—H 键活化以及 3-氧代戊基-4-烯腈与炔烃的环化反应高效进行。通过区域选择性形成CO和CC键,可以以良好的产率获得具有多个取代基的各种2H-吡喃。涉及羟基炔酸酯的转化通过进一步的分子内酯交换过程产生具有呋喃[3,4- b ]吡喃骨架的产物。与传统的“1-氧三烯途径”不同,该方法合成有用的2H-吡喃的方法在底物易得、产物稳定易衍生化、操作过程温和便捷、步骤和原子经济性等方面具有一定的亮点。
Synthesis of γ-Acetoxy β-Keto Esters Through Regioselective Hydration of γ-Acetoxy-α,β-alkynoates
作者:Tapas R. Pradhan、Kishor L. Mendhekar、Debendra K. Mohapatra
DOI:10.1021/acs.joc.5b00400
日期:2015.6.5
The At(I)-catalyzed regioselective hydration of gamma-acetoxy-alpha,beta-acetylinic ester by the assistance of a neighboring carbonyl group has beets developed. Varieties of simple primary, secondary, and tertiary gamma-acetoxy-alpha,beta-acetylinic esters, even those bearing sensitive functional group in the remote reaction sites, are selectively hydrated to the corresponding beta-keto esters. The reaction' tolerates a wide variety of other carboxylates, such as benzoates, propionates, acrylates, and pivalates, including chiral carboxylates with retention of the configuration. The broad substrate scope, including the derivatization of complex natural products and neutral and open air conditions, makes this atom economical approach very practical. O-18 labeling experiments disclose that the oxygen transposition occurs from the carboxylate group to the triple bond, not from water.