Search

[reaction: see text] A synthesis of 28, the carbon framework of the eleutherobin aglycone, is reported in a 15-step sequence from readily available starting materials. The tandem Diels-Alder reaction of 6 and 7 to produce 18, in which three new rings and six new stereocenters are formed, is a key step in the reaction sequence.

Abstract: An efficient, three-component, microwave-mediated cyclization to prepare the 3,5-disubstituted 2H-pyrrol-2-one core of the bis-indole alkaloid, violacein, is described. Preliminary results indicate an iterative, thermally driven, condensation of a γ-ketoester, ammonium acetate, and isatin in polyethylene glycol. This methodology is an effective and environmentally benign route to prepare a series of violacein analogs in good overall yields. [Copyright &y& Elsevier]