Dimerisation of levonorgestrel in solid state ultraviolet light irradiation.

UV-irradiation of levonorgestrel (1) in the crystalline state under a nitrogen atmosphere yielded its dimer, [17 alpha[1R-(1 alpha,2 beta,4a beta,4b alpha,10a alpha)]]-13-ethyl-17- [4- (2-ethyl-1,2,3,4a,4b,5,6,7,9,10,10a-dodecahydro-7-oxo-1-phenant renyl)-1- methylen-2-oxo-butoxy]-18,19-dinorpregna-4-en-20-in-3-one(3) , as the principal photoproduct. It was characterized from its spectral and analytical data. The single crystal X-ray crystallographic data of 1 indicated the possibility of its photochemical dimerisation.

Photostability studies of ouabain, alpha-acetyldigoxin and digoxin in solid state.

Ouabain, alpha-acetyldigoxin and digoxin were subjected to irradiation using different light sources in crystalline state and their respective yields of photoproducts were determined densitometrically. alpha-Acetyldigoxin was found to be less stable than digoxin yielding a higher percentage of photoproducts under each light source examined. Ouabain showed photostability under the conditions of investigation.