Cascade Reactions of Methyl 2-Chloro-2-cyclopropylideneacetate with Five- and Seven-Membered Cyclic Dienolates: A Novel Approach to the Bicyclo[4.2.1]nonane Segment of the Skeleton of Mediterraneols

The MIMIRC (Michael-Michael-Ring Closure) reaction of methyl 2-chloro-2-cyclopropylideneacetate (5) with the cyclic dienolates 6a, 6c, and the one derived from 11-R under aprotic conditions gave the tricyclic adducts 7a, 7c, and 10-R, respectively, in moderate to good yield. Compound 10-R is conceived as a potential intermediate for the synthesis of the biologically active marine diterpenes mediterraneol 1.