Et2N(CH2)20 Scheme 47


Cyclisation is observed also with tomoxifen (163b, R=Et).167 Dihydroxysubstituted stilbenes such as stilboestrol (166) and dienoestrol (167) are likewise cyclised (Schemes 48 and 49). From the former drug either a tetrahydrophenanthrenedione (168) or an aromatised dihydroxyphenanthrene (169) have been obtained under different conditions. From the latter one, hydrogen sigmatropic shift, isomerisation and cyclisation finally give dione (170). 168-170

Scheme 48

2.5 Dermatologicals

Photostability is a particularly significant characteristic for drugs for external use. Some indications about the photostability of drugs in ointments and eye-drops are given in Sec. 3.

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