D. Spitzner, A. Engler, P. Wagner
1987
Citations
0
Influential Citations
27
Citations
Journal
Tetrahedron
Abstract
Abstract Methyl 2-chlorocyclopropylidenacetate (2-Cl) smoothly [2+4]cycloadds to cyclopentadiene and 2,3-dimethylbutadiene at room temperature. With the donorsubstituted cyclohexadienes 6, 9 at elevated temperatures (60, 120°C respectively) 2-C1 reacts without any observable regioselectivity. In contrast, 2-Cl, when treated with lithium cyclohexadienolates 13 undergoes completely regioselective iterative Michael additions with subsequent intramolecular γ-elimination to give tricyclic γ-ketoesters 16 in good to excellent yields. The products 16 can readily be transformed to multifunctional bicyclo[2.2.2]octane as well as bicyclo [3.2.1]octane derivatives 17. A rationalization of the unprecedented reactivity of 2-Cl on the basis of its available structural features (IP(π), 1JC,C, CC bond length) is offered.