Sulfur Ylide-Mediated [2 + 1] Annulation for the Synthesis of Spiro[cyclopropane-indolizine] Derivatives
Zheng-Yan Li1, Yi-Na Ma1, Xing Zheng1
1National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, School of Chemistry and Environment, Yunnan Minzu University, Kunming 650504, China.
Abstract:
A diastereoselective synthesis of spiro-[cyclo-pro-pane-indo-lizine] derivatives via a [2 + 1] annulation reaction has been developed. This Michael-initiated ring closure of 7-arylmethylidene-6,7-dihydroindolizin-8-(5H)-ones with acyl-stabilized sulfur ylides furnishes a diverse array of densely functionalized spirocyclopropanes in moderate to excellent yields (up to 94%) with generally high to excellent diastereoselectivity (up to >20:1 dr). Further derivatization of these tricyclic scaffold-containing products has been accomplished via free-radical C-N bond coupling or sequential cyclopropane ring-opening followed by heteroatom-mediated 1,5-dicarbonyl cyclization.
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