Construction of a Clock Catalytic System: Highly Efficient and Self‐Indicating Synthesis of Benzoheterocycles at Ambient Temperature. Issue 12 (27th October 2021)

• Record Type: Journal Article
• Authors: Xiong, Wu‐Lin; Peng, Xiao‐Chong; Zhong, Ren‐Yuan; Zheng, Jianwei; Duo, Shuwang; Gong, Shan‐Shan; Sun, Hong‐bin; Sun, Qi
• Is Part Of: Asian journal of organic chemistry. Volume 10:Issue 12(2021)
• Page Start: 3321
• Page End: 3327
• Publication Date: 2021-10-27
• Subjects: clock reaction -- phosphomolybdic acid -- phosphomolybdenum blue -- benzimidazole -- benzothiazole; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; 547.005
• DOI: 10.1002/ajoc.202100508
• Languages: English
• ISSNs: 2193-5807

Abstract

Abstract: Inspired by the mechanism of the clock reaction, we rationally constructed a novel phosphomolybdenum blue (PMB) clock catalytic system for a highly efficient synthesis of benzimidazoles and benzothiazoles simply at ambient temperature. The current PMB clock catalytic system exhibits a sharp decoloration event to announce the depletion of the intermediateconstraint, making this synthetic approach self‐indicating and TLC‐free. 31 P NMR and XPS analysis of PMBcatalyst showed that only two Mo 6+ atoms are reduced to Mo 5+ atoms in the Keggin structure due to the moderate reducibility of benzimidazoline and benzothiazoline intermediates. Thus, the active Keggin‐type POM cluster could be well maintained in DMSO during the redox cycling of phosphomolybdic acid (PMA) and PMB. 1 H NMR tracing experiment not only confirmed the proposed reaction mechanism but also showed that PMB exerts Lewis acid catalytic activityat the early phase of the reaction other than the expected redox catalytic activity. Abstract : A novel phosphomolybdenum blue (PMB) clock catalytic system has been constructed featuring highly efficient synthesis of benzimidazoles and benzothiazoles at ambient temperature and color‐based reaction process self‐indication. 31 P NMR and XPS analysis of PMB catalyst and 1 H NMR tracing of the reaction process provided more insights into the working mechanism of PMB clock catalytic system.