ChemInform Abstract: Organocatalytic Enantioselective Formal Synthesis of Bromopyrrole Alkaloids via Aza‐Michael Addition.

Abstract

Organocatalytic Enantioselective Formal Synthesis of Bromopyrrole Alkaloids via Aza-Michael Addition. -An enantioselective aza-Michael addition to protected 4-hydroxy butenal (II) using pyrroles (I) and (IV) as the N-centered nucleophile is utilized to construct the nitrogen-substituted stereogenic carbon center in bromopyrrole alkaloids. The aza-Michael product (IIIa) is converted to the key intermediate (IX) via lactamization using a Staudinger-type reductive cyclization, which is previously used in the total synthesis of bromopyrrole alkaloid natural products. -(LEE, S.-J.; YOUN, S.-H.; CHO*, C.-W.; Org. Biomol. Chem. 9 (2011) 22, 7734-7741, http://dx.doi.org/10.1039/c1ob06078c ; Dep. Chem., Kyungpook Natl. Univ., Daegu 702-701, S. Korea; Eng.) -M. Paetzel