Synthesis of (±)-lahadinine B and (±)-11-methoxykopsilongine

6,7-Dimethoxytryptamine 11 was converted into the homoannular diene 19 which underwent a Diels–Alder reaction with acryloyl chloride to give 20. Subsequent radical decarboxylation in the presence of (PhSe)2 provided 22, which was converted into (±)-lahadinine B 1 and (±)-11-methoxykopsilongine 2, thus confirming their structures.