2911-86-6Relevant articles and documents
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 (2007/10/02)
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.
TANDEM MICHAEL-MICHAEL-RING CLOSURE (MIMIRC) REACTIONS; ONE-POT STEROID TOTAL SYNTHESIS-(+/-)-9,11-DEHYDROESTRONES
Posner, Gary H.,Mallamo, John P.,Black, Alison Y.
, p. 3921 - 3926 (2007/10/02)
A new sequence of reactions involving tandem Michael-Michael-ring closure (MIMIRC) has been developed for efficient formation of three C-C bonds in one reaction vessel.The terminal ring closure reaction proceeds via either a 1,3- or a 1,6-cyclization, and this methodology also serves for construction of quaternary C centers.The usefulness of MIMIRC reactions is demonstrated by efficient assembly of cyclopropyl ketones and of trans-1-hydrindanones such as (+/-)-9,11-dehydroestrone 1b.This one-pot approach represents the shortest known convergent total synthesis of a steroid, and subsequent straightforward transformations lead directly to natural (+/-)-estrone.
