Aromatic heteroannulation via metalation-cyclization of N-acyl-2-chlorobenzenesulfonamides and N-acylbenzenesulfonamides
摘要:
N-Acyl-2-chlorobenzenesulfonamides 7a-d undergo competitive metal-halogen exchange and or alpha-deprotonation reactions when treated sequentially with sodium hydride and n-butyllithium. The o-lithio intermediates derived from metal-halogen exchange and ortho-deprotonation undergo cyclization to afford 3-substituted 1,2-benzisothiazole 1,1-dioxides 10a-d and 3-substituted 7-chloro-1,2-benzisothiazole 1,1-dioxides 14a-d, respectively. Reaction time-temperature data show evidence for the slow conversion of the lateral dianion of N-acetyl-2-chlorobenzenesulfonamide (7a) to the corresponding N,ortho-dialkali salt. 1,2-Benzisothiazole 1,1-dioxides 14a-d were obtained in good yield and free from products resulting from metal-halogen exchange by treatment of sulfonamides 7a-d with 2 equiv of LDA in THF. In the presence of 2 equiv of LDA, N-acylbenzenesulfonamides devoid of or containing only weakly acidic alpha-hydrogens undergo alpha-deprotonation-cyclization to afford the respective 1,2-benzoisothiazole 1,1-dioxides.
Facile synthesis of acyl sulfonamides from carboxyic acids using the Mukaiyama reagent
作者:Ling Chen、Guanglin Luo
DOI:10.1016/j.tetlet.2018.12.030
日期:2019.1
A fast and convenient method using the Mukaiyama reagent was developed to prepare acyl sulfonamides from carboxylic acids and sulfonamides. This methodology is effective for a range of acids and sulfonamides proceeding in moderate to good yields with the majority of reactions complete within one hour under the optimized condition.
A new and efficient PdII‐catalyzed intermolecularannulation of N‐benzoylsulfonamide with allenes for the synthesis of 3,4‐dihydroisoquinolin‐1(2H)‐ones is reported. This CH functionalization is compatible with ambient air and moisture, and it can be applied to terminal or internal allenes with different synthetically attractive functional groups. Control experiments and a kinetic isotope effect study
A convenient method for the preparation of acylsulfonamide libraries
作者:Claudio F Sturino、Marc Labelle
DOI:10.1016/s0040-4039(98)01240-4
日期:1998.8
The preparation of an acylsulfonamide library is described using resin bound EDC (1-(3 dimethylaminopropyl)-3-ethylcarbodiimide). A polymer supported sulfonic acid (A-15) is used as a scavenger to remove dimethylaminopyridine and purification only involves filtration of the reaction mixture. This method provides the acylsulfonamides products in good yields and purity. (C) 1998 Elsevier Science Ltd. All rights reserved.