ISSN:
0170-2041
Keywords:
Steroids
;
Titanium amides
;
Ester enolates
;
Dienone-benzene rearrangement
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Regioselective Reactions at the 17-Oxo Group of Androsta-1,4-dine-3,17-dione after in situ Protection with Titaniumtetrakis(dimethylamide)After in situ protection of androsta-1,4-diene-3,17-dione (1) with titaniumtetrakis(dimethylamide) (10) at -20°C to -30°C, the lithium enolates of methyl methoxyacetate (2a) and ethyl acetate (2b) react regio- and stereoselectively at the 17-position to give the 17-hydroxy-17α-pregnanes 12 and 6. Dehydration of 12 and 6 furnishes the 17(20)-olefins 13 and 14, intermediates for the synthesis of corticoids and gestagens. The reaction of 1 with 10 and 2a at -60°C gives byproducts of a dienone-benzene rearrangement of the A-ring. The reactions of 1 with 2a and 2b without titaniumtetrakis-(dimethylamide) (10) proceed regioselectively at the 3-position or nonregioselectively at the 3- and 17-positions, respectively.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.1993199301209
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