METHODS FOR INDOLE ALKALOID SYNTHESIS: REACTIONS OF N-ARYLSULFONYLENAMINES WITH ELECTROPHILES. AN EXPEDITIOUS SYNTHESIS OF (+/-)-EBURNAMONINE.
Treatment of 4 with MCPBA gave 9.The pentacyclic amide 3 on exposure to cyanogen chloride gave the cis-chloro-hydrin 20, and the geminal dichloride 21.When 21 was treated with HCl/MeOH it rapidly rearranged to eburnamonine lactam 22.