| Abstract
| - 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 alleneintermediates (e.g.,17). This leads to the formation of angularly fused triquinanes (e.g., 20) inwhich each of the rings is functionally differentiated. Bicyclo[6.3.0]undecadienones (e.g., 36) arethe 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 astrained allene intermediate. The synthetic scope and mechanism of these and related transformations are discussed.
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