作者:Eckhard Ottow、Arwed Cleve、Günter Neef、Wolfgang Schwede
DOI:10.1002/prac.19973390164
日期:——
In a highly diastereoselective fashion novel 11 beta, 17 beta-diaryl steroids 17 and 18 were synthesized via Birch-type reduction [1] of styrylic precursors 11 and 15. Both precursors were readily available by Suzuki-type coupling reactions [2] of aromatic boronic acids [3] and the corresponding enol triflates 6, 10, and 14. Regioselective 17-enol triflate formation in presence of a 11-keto function could be demonstrated in case of steroid 5. The remarkably high degree of stereoselectivity observed parallels results from the natural series [4] and demonstrated a broader applicability of such single electron transfer reductions in stereoselective transformations on the steroid skeleton.