Enantioselective synthesis of an axially chiral 1,7-naphthyridine-6-carboxamide derivative having potent antagonist activity at the NK1 receptor

A new and highly potent NK1 antagonist, (aR,9R)-3 [(aR,9R)-7-[3,5-bis(trifluoromethyl)benzyl]-8,9,10,11-tetrahydro-9-methyl-5-(4-methylphenyl)-7H-[1,4]diazocino[2,1-g][1,7]naphthyridine-6,13-dione], was atropdiastereoselectively synthesized in good yield by cyclization of the chiral intermediate 6b.