General route to the total synthesis of sempervirine analogues containing modified E rings, potential cytostatics

Sempervirine analogues 13a–c with different E rings have been obtained via inverse electron demand Diels–Alder reactions of 5-acetyl-3-(methylsulfanyl)-1,2,4-triazine with cyclic enamines (formation of D and E rings) followed by Fischer indole synthesis under microwave irradiation on solid support (formation of A and B rings) and subsequent annulation of indole derivatives 10a–c via a directed metallation route (formation of C rings).