Towards the Total Synthesis of Saponaceolides: Synthesis of cis-2,4-Disubstituted 3,3-Dimethylmethylenecyclohexanes.

Controlling diastereoselectivity by metal coordination: In the case of 3,3-dimethylmethylenecyclohexanes 2-a structural unit present in many interesting natural products-the thermodynamically less stable cis-2,4-disubstituted compounds become available through a cyclization event wherein the configuration is determined by a carbopalladation step. Both the cycloisomerization of 1,7-enynes 1 and the intramolecular Heck-type reaction of compounds of type 3 provide the cis product as the major product.