Vaidya T, Manbeck GF, Chen S, Frontier AJ, Eisenberg R. Divergent reaction pathways of a cationic intermediate: rearrangement and cyclization of 2-substituted furyl and benzofuryl enones catalyzed by iridium(III).
J Am Chem Soc 2011;
133:3300-3. [PMID:
21322633 DOI:
10.1021/ja111317q]
[Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In contrast to 2-substituted pyrrole enones, furyl and benzofuryl enones do not undergo the Nazarov electrocyclization. Instead, these furyl and benzofuryl enones exhibit unusual rearrangement sequences in the presence of catalytic amounts of [IrBr(CO)(DIM)((R)-(+)-BINAP)](SbF(6))(2) (1; DIM = diethylisopropylidene malonate) and AgSbF(6) (1:1). A 1,2-H shift followed by intramolecular Friedel-Crafts alkylation leads to synthetically valuable cyclohexanones with furanylic quaternary centers. The electrophilicity of 1 is essential for this rearrangement.
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