Cooperative catalysis by bovine serum albumin-iodine towards cascade oxidative coupling-C(sp(2))-H sulfenylation of indoles/hydroxyaryls with thiophenols on water

Org Biomol Chem. 2016 Jun 22;14(25):6111-8. doi: 10.1039/c6ob00930a.

Abstract

Cooperative cascade catalysis by bovine serum albumin (BSA)-iodine allows for the first time the performance of C(sp(2))-H sulfenylation of indole from readily available thiophenol (-SH bond) via in situ generation/cleavage of disulfide (S-S bond) in air under aqueous conditions, whereas BSA or I2 individually do not permit this two step sequence to occur in the same pot towards C-S bond formation. This green cooperative protocol is extendable to sulfenylation of hydroxyaryls (i.e. 2-naphthol or 4-hydroxycoumarin) with diverse thiols (aryl/heteroaryl) without using any toxic metal catalysts, bases or oxidants, thus rendering the process environmentally and economically reliable. Further, the gram scale synthesis of a COX-2 inhibitor (3-(pyridin-2-ylthio)-1H-indole), regioselectivity and recyclability (up to four cycles) are the additional merits of this cooperative cascade bio-chemocatalytic (BSA-I2) protocol. Moreover, HPLC and ESI-MS provide powerful insights into the mechanistic aspects of the above cascade sulfenylation reaction.

MeSH terms

  • Animals
  • Catalysis
  • Cattle
  • Disulfides / chemical synthesis*
  • Disulfides / chemistry
  • Indoles / chemistry*
  • Iodine / chemistry*
  • Oxidation-Reduction
  • Phenols / chemistry*
  • Serum Albumin, Bovine / chemistry*
  • Sulfhydryl Compounds / chemistry*
  • Water / chemistry*

Substances

  • Disulfides
  • Indoles
  • Phenols
  • Sulfhydryl Compounds
  • Water
  • Serum Albumin, Bovine
  • thiophenol
  • Iodine