Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... Synthons for 11-deoxyprostanoids and 11-ketosteroids are available via intramolecular Diels-Alder reactions between oxygenated dienes and attached butenolides. ... All chiral substances were produced as racemates; a single enatiomer is shown for simplicity. All yields cited ...