Steroid aromatization estrogens

Except for a number of aromatic estrogens, the majority of steroids are nonfluorescent. Many steroids react with concentrated sulfuric and phosphoric acid to form fluorescent derivatives, but the lack of selectivity and the formation of a large number of uncharacterized products limit the application of this method in drug testing. 

Cyclization with the participation of hydroigrl groups or double bonds equivalent to them with aromatic rings is used in the syntheses of estrogens (aromatic ring A Schemes 49, 84, 88) or intermediates for the production of nonaromatic steroids (aromatic ring C Scheme 51). On the basis of the cyclization of a model tricyclic carbinol (81) under the action of 90% sulfuric acid, it was shown that when R = Me the formation of a cyclo-pentanophenanthrene derivative (83) takes place predominantly, while when R = H the spirane derivative (85) is the main product. This was explained by the comparative stabilities of the intermediate carbonium ions (82) and (84). When R = H, the tertiaiy carbonium ion (84) leading to the spirane (84) is more stable, and when R = Me the formation of the isomeric tertiary ion (82) is possible, and this cyclizes to the product (83) [55] (Scheme 88). 

The structurally simplest steroids, the aromatic A ring estrogens, have ironically proven most difficultly accessible because this aromatic ring is not found in any of the plant sterols available in commercial quantities. The main task of partial synthesis from naturally occurring material thus becomes... 

The female of mammalian species secretes a series of steroid hormones characterized by an aromatic A ring and the lack of a side chain at the 17 position. These compounds serve as regulators in the reproductive processes of the species. The name (estrogens) comes from the fact that in some lower animals the elaboration of this type of compound is directly involved with the phe-... 

They also reported that on the basis of a review of data on over 2000 chemicals that have been tested in various in vitro and/or in vivo assays, all chemicals showing estrogenic properties contained a ring structure. All except five of the ring structures were aromatic (the exceptions being four steroids and the pesticide kepone). Table 18.1 illustrates the presence of these features in various categories of chemicals. 

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