Step‐Economical Route to 2‐Amido‐3‐bromobenzo[
b
]thiophenes
via
Ynamide Formation and Selectfluor‐Mediated Oxidative Bromocyclization
摘要:
AbstractA one‐pot synthesis of 2‐amido‐3‐bromobenzo[b]thiophenes based on C−N coupling and oxidative bromocyclization reactions was developed. This enables a modular approach to obtain diverse substituents at the C2 position of benzothiophenes by employing structurally modified sulfonamides. Oxidative cyclization was driven by Selectfluor and represents a previously unreported recycling method for the bromide anion byproducts of the C−N bond coupling step. The details of the study are described fully herein.
Synthesis of 2,3-Dihydrobenzo[b]thiophen-3-amine 1,1-Dioxide Derivatives via LDA-Mediated Cyclization of o-(Alkylsulfonyl)benzyl Azides with Denitrogenation
摘要:
A new and efficient method for the synthesis of 2,3-dihydrobenzo[b]thiophen-3-amine 1,1-dioxide derivatives has been developed. Thus, treatment of o-(alkylsulfonyl)benzyl azides, which are readily obtainable from commercially available starting materials by easily operational sequences, with lithium diisopropylamide (LDA) in THE at -78 degrees C gives, after aqueous workup, 2,3-dihydrobenzo[b]thiophen-3-amine 1,1-dioxides. These products can be isolated in moderate to fair yields after N-protection with acylating agents.
BF
<sub>3</sub>
Mediated [1,5]‐Hydride Shift Triggered Cyclization: Thioethers Join the Game
作者:Elvira R. Zaitseva、Alexander Yu. Smirnov、Vladimir I. Timashev、Vadim I. Malyshev、Ekaterina A. Zhigileva、Andrey A. Mikhaylov、Michael G. Medvedev、Nadezhda S. Baleeva、Mikhail S. Baranov
DOI:10.1002/ejoc.202200547
日期:2022.7.7
1,5-Hydride shift triggered the cyclization of 2-(2-(benzylthio)benzylidene)malonates to thiachromanes, which are presented for the first time. Boron trifluoride as a reaction promotor is the key of this C−H activation success. Quantum chemical calculations have shown that the studied reaction proceeds via a O–BF2–O chelate, which was confirmed by NMR-analysis.
Step‐Economical Route to 2‐Amido‐3‐bromobenzo[
<i>b</i>
]thiophenes
<i>via</i>
Ynamide Formation and Selectfluor‐Mediated Oxidative Bromocyclization
作者:Su Jeong Hong、Chang Ju Yoon、Hee Nam Lim、Hyun‐Suk Yeom
DOI:10.1002/ejoc.202101093
日期:2021.11.8
AbstractA one‐pot synthesis of 2‐amido‐3‐bromobenzo[b]thiophenes based on C−N coupling and oxidative bromocyclization reactions was developed. This enables a modular approach to obtain diverse substituents at the C2 position of benzothiophenes by employing structurally modified sulfonamides. Oxidative cyclization was driven by Selectfluor and represents a previously unreported recycling method for the bromide anion byproducts of the C−N bond coupling step. The details of the study are described fully herein.
Synthesis of 2,3-Dihydrobenzo[b]thiophen-3-amine 1,1-Dioxide Derivatives via LDA-Mediated Cyclization of o-(Alkylsulfonyl)benzyl Azides with Denitrogenation
A new and efficient method for the synthesis of 2,3-dihydrobenzo[b]thiophen-3-amine 1,1-dioxide derivatives has been developed. Thus, treatment of o-(alkylsulfonyl)benzyl azides, which are readily obtainable from commercially available starting materials by easily operational sequences, with lithium diisopropylamide (LDA) in THE at -78 degrees C gives, after aqueous workup, 2,3-dihydrobenzo[b]thiophen-3-amine 1,1-dioxides. These products can be isolated in moderate to fair yields after N-protection with acylating agents.