Novel Regioselective Formation of S- and N-Hydroxyl-Alkyls of 5-(3-Chlorobenzo[b]Thien-2-yl)-3-Mercapto-4H-1,2,4-Triazole and A Facile Synthesis of Triazolo-Thiazoles and Thiazolo-Triazoles. Role of Catalyst and Microwave

Abstract

Regioselective alkylation of 5-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole (1) with hydroxy alkylating agents 2, 3, 13, and the 2,3-O-isopropylidene-1-O-(p-tolylsulfonyl)-glycerol (10) afforded the corresponding S-alkylated derivatives 6, 7, 11, and 14 under both conventional and microwave irradiation conditions; bentonite as a solid support gave better results, with no change in regioselectivity. A facile intramolecular dehydrative ring closure of 6, 7, 11, and 14 using K₂CO₃ in DMF afforded the corresponding fused triazolo-thiazines and thiazolo-triazole 17–19. The isopropylidenes and acetyl derivatives of the products were prepared.

Keywords:

• 1,2,4-Triazoles
• regioselectivity
• acyclonucleoside
• thiazolo-triazole
• triazolo-thiazines
• microwave
• solid support

Present address of E. S. H. El-Ashry: International Center for Chemical and Biological Sciences, HEJ Research Institute of Chemistry, University of Karachi, Karachi, Pakistan.

M. R. Aouad is on leave from the Ministry of High Education and Scientific Research, Algeria.

Notes

∗See schemes.