Access to [6.4.0]carbocyclic systems by tandem metathesis of dienynes.: A step toward the synthesis of a preD3-D3 transition state analogue

A new approach to the synthesis of linearly fused 6-8-6 tricarbocyclic systems, tandem ring-closing metathesis of dienynes, allows access to compounds with a carbon framework analogous to the proposed transition state of the isomerization of previtamin D-3 to vitamin D-3.