Synthesis of Benzo[4,5]thiazolo[2,3-c][1,2,4]triazole Derivatives via C-H Bond Functionalization of Disulfide Intermediates

Abstract

Many nitrogen- and sulfur-containing heterocyclic compounds exhibit biological activity. Among these heterocycles are benzo[4,5]thiazolo[2,3-c][1,2,4]triazoles for which two main synthetic approaches exist. Here we report a new synthetic protocol that allows the preparation of these tricyclic compounds via the oxidation of a mercaptophenyl moiety to its corresponding disulfide. Subsequent C-H bond functionalization is thought to enable an intramolecular ring closure, thus forming the desired benzo[4,5]thiazolo[2,3-c][1,2,4]triazole. This method combines a high functional group tolerance with short reaction times and good to excellent yields.

Oxidative Cyclization of 4‐(2‐Mercaptophenyl)‐Substituted 4H‐1,2,4‐Triazolium Species to Tricyclic Benzothiazolium Salts

“…In analogy to our neutral tricyclic heteroarenes, we hypothesize that the cyclization reaction occurs via a disulfide intermediate. [60] While we have been able to oxidize the thiol 3 h to its disulfide by exposure to dry air, we are generally not able to detect this intermediate in our reaction mixtures. Nevertheless, subjecting the disulfide to our cyclization conditions leads to the formation of 4 h which suggests that the oxidative disulfide coupling could be the rate-limiting step of the cyclization reaction as opposed to not the disulfide not being a part of the reaction mechanism.…”

“…In analogy to our neutral tricyclic heteroarenes, we hypothesize that the cyclization reaction occurs via a disulfide intermediate [60] . While we have been able to oxidize the thiol 3 h to its disulfide by exposure to dry air, we are generally not able to detect this intermediate in our reaction mixtures.…”

Synthesis of Few New Carrier Polymers Derived from 2-hydrazinylbenzo[d]thiazole

“…Compound [1] has been synthesized via reacting 2-mercaptobenzothiazol with hydrazine hydride in ethanol. FTIR of compound [1] display the appearance bands at (3396 cm -1 and 3278 cm -1 ) have been respectively a result of the asymmetrical and symmetrical stretching vibrations of the (-NH 2 ) group and disappearance (SH) group at 2357 cm -1.…”

“…Compound [2] produce from reaction compound [1] with maleic anhydrides in DMF. Compound [2] was identified by FTIR spectroscopy.…”

“…Nitrogen-and sulfur-containing heterocycles can be found in a wide range of the natural products, commercially available drugs, agrochemicals, and compounds with the potential of becoming active pharmaceutical materials. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Which is why, there have been continued interests in the development of new approaches for synthesizing the biologically active fused heterocycles, which incorporate the benzo-thiazole fragment. 15 2-mercapto-benzothiazole presents great interests in pharmacology and chemistry due to its wide range of biological activities.…”