A New And Efficient Synthesis Of 6-[(5s,9r)-9-(4-Cyanophenyl)-3-(3,5-Dichlorophenyl)-1-Methyl-2,4-Dioxo-1 ,3,7-Triazaspiro[4.4]Non-7-Yl]Nicotinic Acid, A Potent Lfa-1/Icam Inhibitor

An efficient synthesis of 64(5S,9R)-9-(4-cyanophenyl)-3-(3,5-dichlorophenyl)-1-methyl-2,4-dioxo-1,3,7-triazaspiro[4.4]non-7-yl]nicotinic acid 1 is described. This new process involves an in situ protection of 6-chloronicolinic acid as trimethylsilyl ester followed by coupling with spirocyclic hydantoin core 2 to give the target product in 89% overall yield after one-pot deprotection and final API recrystallization.