Synthesis of angular triquinanes from 1-alkynylbicyclo[3.2.0]hept-2-en-7-ones. A tandem alkoxy-Cope ring expansion/transannular ring closure reaction

S. K. Verma, E. B. Fleischer, H. W. Moore

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Addition of ethenyllithium reagents to the carbonyl group of dialkyl squarate-derived 1-alkynylbicyclo[3.2.0]hept-2-ene-7-ones (15), followed by a TBAF workup, results in a low-temperature anion-accelerated alkoxy-Cope rearrangement which proceeds by way of a strained cyclic allene intermediates (e.g.,17). This leads to the formation of angularly fused triquinanes (e.g., 20) in which each of the rings is functionally differentiated. Bicyclo[6.3.0]undecadienones (e.g., 36) are the major products when the reactions are quenched with aqueous bicarbonate rather than TBAF. Under analogous conditions 2-alkylidene-1-alkynylbicyclo[3.2.0]heptan-7-ones also give bicyclo-[6.3.0]undecadienones by a mechanism that was established to involve a 1,5-hydrgen shift in a strained allene intermediate. The synthetic scope and mechanism of these and related transformations are discussed.

Original languageEnglish (US)
Pages (from-to)8564-8573
Number of pages10
JournalJournal of Organic Chemistry
Issue number25
StatePublished - Dec 15 2000


ASJC Scopus subject areas

  • Organic Chemistry

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