Difluoroboron Complexes as Versatile Precursors for Steroid Modification. Lumiestrone-Based Steroid Derivatives: Synthesis and Structural Studies.

A preparation method for steroid-based difluoroboron complexes has been developed using lumiestrone as a steroid example. Previously inaccessible lumiestrone-based difluoroboron complexes annulated at positions 16 and 17 of the D ring have been prepared. Such difluoroboron complexes may have large synthetic potential for heterofunctionalization of steroids at the D ring. An application of a borylation mixture AcO-BF⋅OEt significantly simplify the preparation of steroid "dimers" bearing two estrone moieties connected at positions 2 and 2' via a linker. Crystal structures of key representatives have been determined by X-ray diffraction.