ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
An approach to a new class of cyclic hydroxamic acids is described leading to a formal combination of a benzoxazine subunit related to some natural aglucones occurring in plants with the steroidal skeleton from two members of the estra-1,3,5(10)-triene series. The annelation procedure for a 4-hydroxy-1,4-oxazine moiety to the aromatic A-ring in estrone (1) and 1-hydroxy-4-methylestra-1,3,5(10)-trien-17-one (7), used as steroidal precursors, proceeds in four or three steps, respectively (Schemes 1 and 2, resp.). First, a 2-nitro group is introduced regioselectively by a novel nitrosation-oxidation procedure or by conventional nitration (→ nitrophenols 2 and 8). Reaction of the phenolic unit of 2 and 8 with methyl bromoacetate or ethyl chlorooxoacetate gives rise to the nitro esters 3, 4, 9, and 10, which are subjected to reductive cyclization either by means of Zn dust in ammonium chloride solution (for the acetates) or of H2/Pt(S)/C (for the sensitive oxalates). Hence, the novel cyclic hydroxamic acids 5, 6, 11, and 12 of the estra-1,3,5(10)-triene series are obtained.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19970800807
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