Piperidin-4-Ylidene Substituted Tricyclic Compounds

Prescribed drugs containing nitrogen heterocycles: an overview

“… 382–388 Loratadine 362 can be produced via various routes. It can be effectively synthesized, based on the formerly reported approaches, 389 starting from the 8-chloro-5,6-dihydro-11 H -benzo[5,6]cyclohepta[1,2- b ]pyridin-11-one ketone 356, which upon treatment with an appropriate Grignard reagent 355 afforded the respective tertiary carbinol that was subsequently dehydrated in acidic media giving the 8-chlorol-1-piperidiylidene derivative 359. The later then was treated with ethylchloroformate under refluxing benzene to afford compound 361 which was transformed to the desired target product, loratadine 362 by refluxing in xylene.…”