Diastereoselective [4 + 1] Cycloaddition of Alkenyl Propargyl Acetates with CO Catalyzed by [RhCl(CO)2]2
摘要:
A class of alkenyl propargyl acetates, RCH(OAc)C CC(CH3)=CH2 (5), are found to undergo [4 + 1] cycloaddition with CO (1 atm) in the presence of [RhCl(CO)(2)](2) in refluxing 1,2-dichloroethane to give cyclopentenones (6) in good yields. It has been demonstrated that, when the R group of 5 is a phenyl group bearing o-electron-withdrawing substituents up to 10:1 diastereoselectivity and 96% yield can be achieved for the [4 + 1] cycloaddition. This process provides a convenient method to construct highly functionalized cyclopentenones that are useful in organic synthesis.
Gold-catalyzed (4 + 2)-annulations between α-alkyl alkenylgold carbenes and benzisoxazoles with reactive alkyl groups
作者:Bhanudas Dattatray Mokar、Prakash D. Jadhav、Y. B. Pandit、Rai-Shung Liu
DOI:10.1039/c8sc00986d
日期:——
This work reports new (4 + 2)-annulations of α-alkyl vinylgold carbenes with benzisoxazoles to afford 3,4-dihydroquinoline derivatives with high anti-stereoselectivity. The annulations are operable with carbenes in both acyclic and cyclic forms. This reaction sequence involves an initial formation of imines from α-alkylgold carbenes and benzisoxazoles, followed by a novel carbonyl-enamine reaction
Gold‐Catalyzed [3+2]‐Annulations of α‐Aryl Diazoketones with the Tetrasubstituted Alkenes of Cyclopentadienes: High Stereoselectivity and Enantioselectivity
作者:Ching‐Nung Chen、Wei‐Min Cheng、Jian‐Kai Wang、Tzu‐Hsuan Chao、Mu‐Jeng Cheng、Rai‐Shung Liu
DOI:10.1002/anie.202012611
日期:2021.2.23
This work reports gold‐catalyzed [3+2]‐annulations of α‐diazo ketones with highly substituted cyclopentadienes, affording bicyclic 2,3‐dihydrofurans with high regio‐ and stereoselectivity. The reactions highlights the first success of tetrasubstituted alkenes to undergo [3+2]‐annulations with α‐diazo carbonyls. The enantioselective annulations are also achieved with high enantioselectivity using chiral
Development of a [2 + 2]-Nitroso/Alkene Cycloaddition Using Sodium Tetrakis[3,5-bis(trifluoromethyl)phenyl]borate Catalyst: Controlled Chemoselectivity of Two Equilibrating Isomeric Intermediates
作者:Jia-Xuan Chen、Prakash D. Jadhav、Ching-Nung Chen、Rai-Shung Liu
DOI:10.1021/acs.orglett.1c01987
日期:2021.8.20
Sodium tetrakis[3,5-bis(trifluoromethyl)-phenyl]borate (NaBArF) catalyzes the [2 + 2] cycloaddition of 1,4-disubstituted cyclopenta-1,3-dien-2-yl esters with nitrsobenzene in toluene, affording two isolable regioisomers of 6-oxa-7-azabicyclo[3.2.0] heptanes, which thermally rearrange into the same 4-aminocyclopent-1-en-3-ones. In the case of 4-substituted cyclopenta-1,3-dien-2-yl esters, their initial
Brønsted Acids Enable Three Molecular Rearrangements of One 3-Alkylidene-2<i>H</i>-1,2-oxazine Molecule into Distinct Heterocyles
作者:Bhanudas Dattatray Mokar、Jinxian Liu、Rai-Shung Liu
DOI:10.1021/acs.orglett.7b03985
日期:2018.2.16
This work describes three different strategies to structurally rearrange one 3-alkylidene-2H-1,2-oxazine molecule into three distinct heterocycles using HOTf, propiolic acid, and silicagel, respectively. The mechanisms of these rearrangement reactions involve three independent routes, including (i) Brønsted acid catalysis, (ii) a synergetic action of Brønsted acids and anions, (iii) a surface-directed
这项工作描述了三种不同的策略,分别使用HOTf,丙酸和硅胶将一个3-亚烷基-2 H -1,2-恶嗪分子结构重排成三个不同的杂环。这些重排反应的机理涉及三个独立的途径,包括(i)布朗斯台德酸催化,(ii)布朗斯台德酸和阴离子的协同作用,(iii)表面定向的化学选择性。
Efficient Synthesis of Cyclopentenones from Enynyl Acetates via Tandem Au(I)-Catalyzed 3,3-Rearrangement and the Nazarov Reaction
作者:Liming Zhang、Shaozhong Wang
DOI:10.1021/ja057327q
日期:2006.2.1
A highly efficient method for the synthesis of versatilecyclopentenones from readily available enynyl acetates via tandem Au(I)-catalyzed 3,3-rearrangement and the Nazarov reaction is developed. Significant substrate flexibility and excellent control of the double bond position in the cyclopentenone ring render this an attractive method for cyclopentenonesynthesis.