Aromatic A-ring Reactions

Reaction of a solution of estrone in acetic acid with nitric acid results in the formation of approximately equal amounts of 2- (19-1) and 4-nitroestrane (19-2). Each of those products can then be converted to the corresponding nitroestradiol, 

Different results are obtained when this reaction is carried out using metal nitrates on solid supports. Reaction of a solution of estrone in THE with montmoriUonite-supported bismuth nitrate gives a 2 1 ratio of 4-nitroestrone (19-2) to 

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