Synthesis of selective 5-HT1B/1D receptor agonist, sumatriptan (1) was accomplished through decarboxylation of 2-carboxy-3-[2-(dimethylamino)ethyl]-N-methyl-1H-indole-5-methanesulfonamide (2) in quinoline with copper powder. The preparation of the acid (2) was effected through the Japp-Klingemann method thus avoiding the need for the formation of hydrazine from diazonium salt. Attempted decarboxylation in N,N-dimethylacetamide resulted in the formation of the beta-carboline (16).
Synthesis of 5-Substituted Indole Derivatives, I. An Improved Method for the Synthesis of Sumatriptan
摘要:
An improved synthesis of sumatriptan (Ib) via Fischer cyclization was achieved by introducing the ethoxycarbonyl group on the N-atom of the sulphonamide moiety in N-methyl-4-hydrazinobenzenemethanesulphonamide (7). As a result, substitution on the benzylic carbon of the indole nucleus could be avoided; however, formation of 1,1-bis-(indol-2-yl)-4-dimethylaminobutane-type by-product (19) was observed. The indolization procedure was optimized to suppress the unwanted side reaction. The N-protection of the sulphonamide moiety was found to be beneficial regarding the purification of the 3-[2-(dimethylamino)ethyl]-N-ethoxycarbonyl-N-methyl-1H-indole-5-methanesulphonamide (18).