Chemistry of the new immunosuppressant KH-1060: new synthons and x-ray evidence for unique side-chain geometry

The new vitamin D analog KH-1060 has immunosuppressive activity greater than of cyclosporin A. We report a new CD synthon 4 for the vitamin D analog KH-1060 and the synthesis and x-ray structure of related cholesterol derivative 15. Williamson ether synthesis provides a route to this class of compound using a new CD intermediate 8. The x-ray structure of 14 suggests that the immunosuppressive activity of KH-1060 may lie in its unique steroid side chain geometry.