Bronsted acid-mediated annulations of pyrroles featuring N-tethered α,β-unsaturated ketones and esters: Total syntheses of (±)-tashiromine and (±)-indolizidine 209I

This study provides the first report of the construction of tetrahydroindolizines and tetrahydropyrrolo [1,2-a]azepines via Bronsted acid-mediated annulation of pyrroles featuring N-tethered alpha,beta-unsaturated esters. In addition, the Bronsted acid-catalyzed cyclization of pyrroles featuring pendant alpha,beta-unsaturated ketones was applied to complete total syntheses of the indolizidine alkaloids (+/-)-tashiromine and (+/-)-indolizidine 209I. (C) 2018 Published by Elsevier Ltd.