Synthesis of 1(3H)-Imino-2-benzothiophene and 1-Imino-1H-2-benzothiopyran Derivatives by Reactions of Secondary o-(Vinyl)thiobenzamide Derivatives with Iodine

Kobayashi, Kazuhiro; Fujita, Seiki; Hase, Masanori; Morikawa, Osamu; Konishi, Hisatoshi

doi:10.1246/bcsj.80.763

Cited by 20 publications

(1 citation statement)

References 7 publications

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“…to Me 4 Si as internal standard, J in Hz. a-Substituted 2-Bromostyrenes 1a [6], 1b [7], 1c [7], 4a [8], 4b [9], 4c [10], and 4d [11] were prepared by the appropriate reported methods. All other chemicals used in this study were commercially available.…”

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confidence: 99%

Hydriodic Acid‐Mediated Cyclization of α‐Substituted Secondary 2‐Ethenylbenzamides: Synthesis of 2‐Substituted 2,3‐Dihydro‐3,3‐dimethyl‐1H‐isoindol‐1‐ones and 3,3‐Disubstituted (E)‐1‐(Arylimino)‐1,3‐dihydroisobenzofurans

Kobayashi

Fujita

Nakai

et al. 2010

Helvetica Chimica Acta

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A new and facile method for the preparation of 2-substituted 2,3-dihydro-3,3-dimethyl-1H-isoindol-1-ones 3 and 3,3-disubstituted (E)-1-(arylimino)-1,3-dihydroisobenzofurans 6 has been developed. Thus, treatment of N-alkyl(or aryl)-2-(1-methylethen-1-yl)benzamides 2 with concentrated hydriodic acid (HI) in MeCN at room temperature afforded 3. Similar treatment of N-aryl-2-(1-phenylethen-1-yl)benzamide 5 with concentrated HI at 08 afforded 6.Introduction. -We previously reported a synthesis of 3,3-disubstituted-2,3-dihydro-1H-isoindol-1-ones based on iodoamination of a-substituted secondary 2-ethenylbenzamides, which could be prepared by the reaction of a-substituted 2-lithiostyrenes with isocyanates [1]. As an extension of this work, we herein describe the results of our study on HI-mediated cyclization of a-substituted secondary 2-ethenylbenzamides, which provide concise and efficient synthetic routes to 2-substituted 2,3-dihydro-3,3-dimethyl-1H-isoindol-1-ones and 3,3-disubstituted (E)-1-(arylimino)-1,3-dihydroisobenzofurans depending on the a-substituents of a-substituted secondary 2-ethenylbenzamides. The synthesis of 2,3-dihydro-1H-isoindol-1-ones has recently attracted considerable attention owing to the occurrence of biological active compounds containing this heterocyclic system [2]. A number of methods for the synthesis of this system have been developed [3]. However, most of these methods require several steps and/or involve tedious reaction conditions. On the other hand, a few general methods have been reported for the preparation of 1-(alkyl(or aryl)imino)-1,3-dihydroisobenzofuran derivatives [4]. For example, Kunai and co-workers have reported a synthesis of 3,3-disubstituted 1-(tert-octylimino)-1,3-dihydroisobenzofurans by three-component coupling using arynes and tert-octyl isocyanide [4a] [4c]. This class of molecules may be of biological interest, because a number of molecules, which have a related isobenzofuran-1(3H)-one (phthalide) structure, have exhibited a variety of biological activities [5].

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Hydriodic Acid‐Mediated Cyclization of α‐Substituted Secondary 2‐Ethenylbenzamides: Synthesis of 2‐Substituted 2,3‐Dihydro‐3,3‐dimethyl‐1H‐isoindol‐1‐ones and 3,3‐Disubstituted (E)‐1‐(Arylimino)‐1,3‐dihydroisobenzofurans

Kobayashi

Fujita

Nakai

et al. 2010

Helvetica Chimica Acta

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Photoelectrocatalytic [4+2] Annulation for S‐Heterocycle Assembly Enabled by Proton‐Coupled Electron Transfer (PCET)

Cheng,

Xu,

Lin

et al. 2024

Chemistry A European J

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Cross‐dehydrogenative couplings (CDC) present an efficient strategy for the assembly of biorelevant heterocycles, but are thus far largely limited to toxic transition metals and rather harsh reaction conditions. In sharp contrast, we, herein report on a mild photoelectrocatalyzed CDC‐[4+2] annulation enabling the synthesis of functionalized isothiochromenes enabled by a proton‐coupled electron transfer (PCET) strategy. The transformative photoelectrocatalysis obviated toxic transition‐metal, high reaction temperatures, and stoichiometric chemical redox reagents. This approach was characterized by exceedingly mild conditions, ample substrate scope, and a commercially available catalyst. Gram‐scale reactions and a telescoped synthesis route reflected the unique potential in the green synthesis of important S‐heterocycles.

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