Accessing Dihydro-1,2-oxazine via Cloke–Wilson-Type Annulation of Cyclopropyl Carbonyls: Application toward the Diastereoselective Synthesis of Pyrrolo[1,2-<i>b</i>][1,2]oxazine
作者:Pankaj Kumar、Rakesh Kumar、Prabal Banerjee
DOI:10.1021/acs.joc.0c00531
日期:2020.5.15
A convenient additive-free synthesis of dihydro-4H-1,2-oxazines via a Cloke-Wilson-type ring expansion of the aryl-substituted cyclopropane carbaldehydes with the hydroxylamine salt is introduced. Comparatively less active cyclopropyl ketones also follow a similar protocol if supplemented by catalytic p-toluene sulfonic acid monohydrate. The transformation is performed in an open-to-air flask as it
Substituent and Lewis Acid Promoted Dual Behavior of Epoxides towards [3+2]-Annulation Reactions with Donor-Acceptor Cyclopropanes: Synthesis of Substituted Cyclopentane and Tetrahydrofuran
substituents present in both reacting partners produced different products. The C-attack gave functionalized cyclopentane derivatives while the O-attack furnished tetrahydrofuran derivatives via [3+2]-annulation reactions. Moreover, to increase the utility of our method, synthesized diasteriomeric cyclopentane derivatives were converted into synthetically useful cyclopentene and cyclopentanone analog.
Synthesis of Indenopyridine Derivatives <i>via</i>
MgI<sub>2</sub>
-Promoted [2+4] Cycloaddition Reaction of <i>In-situ</i>
Generated 2-Styrylmalonate from Donor-Acceptor Cyclopropanes and Chalconimines
作者:Kamal Verma、Prabal Banerjee
DOI:10.1002/adsc.201800598
日期:2018.10.4
An unexpected MgI2‐promoted [2+4] cycloaddition reaction of in‐situ generated 2‐styrylmalonate from donor‐acceptor cyclopropanes with chalconimines to synthesize highly substituted indenopyridine derivatives under the mild reaction conditions have been developed. Additionally, these derivatives were utilized for the synthesis of highly substituted 9‐membered lactam by oxidative C=C bond cleavage and
Efficient and mild synthesis of highly substituted 2,5-dihydrofuran and furan derivatives via stepwise reaction
作者:Tiantian Wang、Jia Liu、Zhiliang Lv、Hanyu Zhong、Huan Chen、Chunjuan Niu、Ke Li
DOI:10.1016/j.tet.2011.03.038
日期:2011.5
An efficient and mild synthesis of highlysubstituted 2,5-dihydrofuran and furan derivatives from a variety of alkylidene malonates and 1,4-butyne-diol via one-pot reaction was applied. With various conditions of base amount, temperature and time applied to the reaction, the 2,5-dihydrofuran and the furan derivatives could be selectively obtained. Moreover, the formation of furan derivatives with 2
A large array of 3-methylene tetrahydrofurans has been synthesized from propargylic alcohols and activated olefins. The reaction is promoted by copper iodide that is removed at the end of the reaction by simple filtration, affording the desired heterocycles in high yield and purity.