Synthesis of Ellipticine by Hetaryne Cycloadditions − Control of Regioselectivity

We have modified Gribble’s and Moody’s approaches to ellipticines by introducing substituents into the 3,4-didehydropyridine dienophile to control the key cycloaddition step. A chloro substituent at position 2 improved the yields and the regioselectivities of the cycloadditions and the overall efficiency of the synthesis of ellipticine.