Highly diastereoselective synthesis of 11β,17β-diaryl-18a-homo-19-nor steroids
摘要:
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.
Highly diastereoselective synthesis of 11β,17β-diaryl-18a-homo-19-nor steroids
摘要:
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.
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.