A New and Competitive Synthetic Approach for an Antihistamine Agent, Bilastine#

Efforts towards the novel synthesis of second generation non-sedating antihistamine drug, Bilastine was described in this manuscript. This competitive synthetic approach involves the convergent synthesis of Bilastine via simple Friedel-Crafts acylation as an alternate for earlier reported Stille and Suzuki couplings. The selectivity in Friedel-Crafts acylation reaction with chloro acetyl chloride on different substituted arenes was studied and employed the best conditions for the synthesis of Bilastine. Further synthetic approach involves the deoxygenation of aryl ketone to corresponding alkane in single step and finally provides Bilastine with 39% of improved overall yields, utilizing simple and cost-effective reagents, suitable for kilogram scale synthesis. Keywords: Bilastine, friedal craft acylation, chloro acetyl chloride, deoxygenation, benzimidazole, kilogram scale synthesis.