135586-91-3Relevant academic research and scientific papers
Total synthesis with a chirogenic opening move demonstrated on steroids with estrane or 18a-homoestrane skeleton
Quinkert,Del Grosso,Doring,Doring,Schenkel,Bauch,Dambacher,Bats,Zimmermann,Durner
, p. 1345 - 1391 (1995)
A concept of first choice for the synthesis of the title compounds had been proposed by Dane in the late 1930s. It was soon turned down, because the opening move - a chirogenic Diels-Alder reaction - did not work. With Lewis acids as mediators, however, a successful start has been achieved now. With Ti complexes of chelating ligands (Seebach's TADDOLs (= α,α,α',α'-tetraaryl-1,3-dioxolane-4,5-dimethanols)), enantioselective formation of the desired adducts does occur. Efficient total syntheses of 2 and 3a have been accomplished.
E. Dane's Route to Estrone Revisited
Quinkert, Gerhard,Grosso, Michael del,Bucher, Astrid,Bats, Jan W.,Duerner, Gerd
, p. 3357 - 3360 (2007/10/02)
The chirogenic Diels/Alder reactions of the general pattern AB + D -> ABCD (i): 2 + 3 -> rac-8a (major) + rac-9a (minor) (85percent), (ii): 2 + 10a -> rac-11a (89percent) and (iii): 2 + 10b -> rac-11b (90percent), now have been accomplished in the presence of Lewis acid, (i): BF3*Et2O, (ii) or (iii): TiCl4.Case (iii) may be used as the initial move towards (+/-)-norgestrel (rac-14).
