Formation of pyrroloindolines via the alkylation of tryptamines with trichloroacetimidates

Pyrroloindolines and related systems are present in a large number of complex natural products. These core structures have generated considerable synthetic interest, as many of the compounds possess challenging, elaborate structures and interesting biological properties. Recently we have focused on using trichloroacetimidates for the synthesis of these fascinating molecules. Trichloroacetimidates can be used as an electrophilic source of an alkyl group to form the pyrroloindoline directly from tryptamine derivatives. In this manner trichloroacetimidates provide a flexible solution to forming highly functionalized pyrroloindoline core structures, needing only a catalytic amount of a Lewis acid to effect the requisite transformations.