3-(Ethoxycarbonyl)-1,2,3,4-tetrahydro-7-methoxycyclopent[b]indole-3-acetic acid ethyl ester

This compound serves as a protected and substituted tetracyclic core, which is subsequently functionalized to form the final active ingredient. 3-(Ethoxycarbonyl)-1,2,3,4-tetrahydro-7-methoxycyclopent[b]indole-3-acetic acid ethyl ester is a key intermediate in the synthetic pathway for Etrasimod, an S1P1 receptor modulator used for treating moderate-to-severe active ulcerative colitis.