Synthesis of Glycoconjugate Benzothiazoles via Cleavage of Benzotriazole Ring

A concise and efficacious benzotriazole-mediated novel
two-step
protocol has been developed for easy access to glycoconjugate benzothiazoles
from protected carbohydrates. The benzotriazolemethanethione 3, prepared by the reaction of free alcohol with bis­(1H-benzo­[1,2,3]­triazol-1-yl)­methanethione, on treatment with
silanes or stannane under heating or microwave irradiation undergoes
free radical β-scission of N–N bond
and affords diverse range of 2-O-substituted benzothiazoles 4 via cyclative elimination of molecular nitrogen. The structures
of all of the compounds have been elucidated using IR, NMR, MS, and
elemental analysis, and five of them have been characterized by single-crystal
X-ray analysis.