36149-34-5Relevant academic research and scientific papers
Diversity-Oriented Synthesis of Heterocycles: Al(OTf)3-Promoted Cascade Cyclization and Ionic Hydrogenation
Liu, Tianqi,Jia, Wenqiang,Xi, Qiumu,Chen, Yonghui,Wang, Xiaojian,Yin, Dali
, p. 1387 - 1393 (2018)
An efficient and facile method has been developed for the diversity-oriented synthesis of heterocycles. Hexahydrophenoxazines, tetrahydroquinolines, indolines, hexahydrocarbazoles, and lactones were conducted via Al(OTf)3-promoted cascade cyclization and ionic hydrogenation. Furthermore, this protocol was utilized to smoothly prepare piracetam and its key intermediate as well.
Copper-catalyzed aerobic double functionalization of benzylic C(sp3)-H bonds for the synthesis of 3-hydroxyisoindolinones
Nozawa-Kumada, Kanako,Matsuzawa, Yuta,Ono, Kanako,Shigeno, Masanori,Kondo, Yoshinori
, p. 8604 - 8607 (2021/09/02)
A copper-catalyzed aerobic 3-hydroxyisoindolinone synthesis was developed via the benzylic double C(sp3)-H functionalization of 2-alkylbenzamides. In this reaction, molecular oxygen was used as both an oxidant for C(sp3)-H functionalization and an oxygen source. Our method can be extended to diverse benzylic C(sp3)-H bonds and shows excellent functional group tolerance. This journal is
Lithium–Bromide Exchange versus Nucleophilic Addition of Schiff's base: Unprecedented Tandem Cyclisation Pathways
Orr, Samantha A.,Border, Emily C.,Andrews, Philip C.,Blair, Victoria L.
, (2019/08/16)
By exploring lithium–bromide exchange reactivity of aromatic Schiff's bases with tert-butyllithium (tBuLi), we have revealed unprecedented competitive intermolecular and intramolecular cascade annulation pathways, leading to valuable compounds, such as iso-indolinones and N-substituted anthracene derivatives. A series of reaction parameters were probed, including solvent, stoichiometry, sterics and organolithium reagent choice, in order to understand the influences that limit such ring-closing pathways. With two viable reactivity options for the organolithium on the imine; namely, nucleophilic addition or lithium–bromide exchange, a surprising competitive nature was observed, where nucleophilic addition dominated, even under cryogenic conditions. Considering the most commonly used solvents for lithium–bromide exchange, tetrahydrofuran (THF) and diethyl ether (Et2O), contrasting reactivity outcomes were revealed with nucleophilic addition promoted in THF, while Et2O yielded almost double the conversion of cyclic products than in THF.
Phthalimidine synthesis via the direct condensation between phthalide and primary amine in the presence of catalytic amount of InCl3
Takahashi, Ichiro,Matsunaga, Takatoshi,Izumi, Yuuki,Sunada, Yuuki,Kawakami, Nanae,Horino, Yuusuke,Inagaki, Sho,Saitoh, Kenta,Hatanaka, Minoru,Hosoi, Shinzo
supporting information, p. 153 - 158 (2017/06/21)
Background: We previously reported the 1:1 condensation reaction between ophthalaldehyde and primary amine in the presence of 1,2,3-1H-benzotriazole and 2-mercaptoethanol as dual synthetic auxiliaries to provide phthalimidines (2,3-dihydroisoindol-1-ones) under mild reaction conditions in good isolated yields. However, this reaction was found to proceed via dissymmetrization of equi-oxidation stage functionalities (carbonyl groups herein), which would give rise to regioisomer(s) whenever the orientation of substituents in the target molecule phthalimidine was dissymmetrical. In order to overcome such defects, we focused on phthalide, which possessed identical electronic structure with that of target molecule phthalimidine. Thus, the condensation between a phthalide derivative and a primary amine would eliminate a water molecule, but does not accompany with any kind of redox paths. Therefore, dissymmetrical trends possessed by the phthalide derivative should transfer directly to the resulting phthalimidine, and as a result the formation of possible regioisomer(s) can completely be prevented. This strategy has existed as the oldest method of phthalimidine synthesis, however, Lewis acid catalysts utilized in the past were not appropriate to extend its scope. In this report, we demonstrate an improved method of phthalimidine synthesis along this line using InCl3 as a catalyst, which would allow the synthesis of this class to accommodate with the contemporary standard of organic syntheses. Method: In general, aniline (2.0 mmol, used at once as reagent and solvent) was added to the flask containing phthalide (1.0 mmol) and InCl3 (an appropriate amount) under Ar atmosphere over Ca. 3 min with stirring, and the whole mixture was heated at gentle reflux for an appropriate period. After usual work-up, crude products were purified by column chromatography on silica gel. Isolated components were ascertained by 1H NMR spectral comparison with the authentic samples prepared by our former methods. Results: Optimization of the reaction condition was explored using phthalide and aniline. Thus, decrement of yields occurred whenever amounts of InCl3 catalyst were reduced, however, longer reaction periods improved isolated yields every time. Even in the use of 1 mol% of InCl3 catalyst, reaction would complete within a few days. As a result, the direct condensation between phthalide and aniline with the use of a truly catalytic amount of Lewis acid catalyst was made possible for the first time in the history of phthalimidine syntheses. Extension of this strategy to some primary amines other than aniline was successful, too. Based on experimental results, our plausible mechanism was proposed, in which the reaction commenced by nucleophilic attack of an amino group towards 3-position of oxygen-chelated phthalide. Conclusion: We succeeded in the direct condensation reaction between phthalide and primary amine in the presence of a catalytic amount of Lewis acid catalyst, InCl3, for the first time. Although successful examples have thus far been limited to some combination that affords clear reaction mixtures (except for the catalyst) under high-temperature, solvent-free heating, we believe that we have attained a tacit basis to prepare a variety of phthalimidine derivatives possessing a variety of substituent patterns.
Addition of transiently-generated methyl o-lithiobenzoate to imines. An isoindolone annulation
Campbell, James B.,Dedinas, Robert F.,Trumbower-Walsh, Sally A.
, p. 6205 - 6211 (2007/10/03)
Addition of phenyllithium to a mixture of an imine, methyl o-iodobenzoate, and BF3-etherate at -105°C gives good to excellent yields of isoindolones. The transient formation of methyl o-lithiobenzoate is proposed, which is formed by a rapid lithium/iodide exchange reaction of the phenyllithium with methyl o-iodobenzoate in the presence of the imine. The transiently generated anions can then be captured by the BF3-activated imines to form the isoindolones in good to high yield. The reactions conditions are sufficiently mild, and selective, to permit functional groups such carbmethoxy and aryl bromide, which could otherwise react with the added PhLi, to be tolerated.
Schiff Bases as External and Internal Electrophiles in Reactions of Functionalized Organolithium Reagents. A New Route to Isoindoline Derivatives and 1,2,3,4-Tetrahydroisoquinolines
Bradsher, Charles K.,Hunt, David A.
, p. 327 - 330 (2007/10/02)
Reaction of Schiff bases with certain functionalized organolithium reagents is useful in the synthesis of 1,2-diarylisoindolines and 2,3-diarylphthalimidines.Schiff bases derived from 2-(2-bromophenyl)ethylamines on halogen-metal exchange with butyllithium undergo a Parham-type cyclization to yield 1-aryl-1,2,3,4-tetrahydroisoquinolines.
