Synthesis of Thromboxane B₂

Significance

Thromboxane B₂ (TXB2) is a stable metabolite formed from thromboxane A₂ (TXA2) and a major product following blood platelet aggregation. The most interesting part of the synthesis is the formation of the bicyclic acetal in D through intermolecular ketalization followed by ring-closing metathesis. The known intermediate I was subjected to the previously published three-step sequence (N. A. Nelson, R. W. Jackson Tetrahedron Lett. 1976, 17, 3275), to give the target material.