title: A ring contraction of 18,20-cyclo-steroids. Preparation of 18-acetyl-17,18-cyclo-4-androsten-3-one and 18-hydroxyacetyl-17,18-cyclo-4-androsten-3-one.
abstract: The ring contraction of 18 alpha-mesyloxy-20 alpha-hydroxy-18,20-cyclopregn-4-en-3-one (Ib) and 18 alpha-mesyloxy-20 alpha-hydroxy-21-acetyloxy-18,20-cyclo-pregn-4-en-3-one (Id) took place upon exposure to Florisil at 25 degrees C, producing 18 alpha-acetyl-17,18-cycloandrost-4-en-3-one (IIa) and 18 alpha-acetoxyacetyl-17,18-cycloandrost-4-en-3-one (IIb) respectively. A similar ring contraction of 18 alpha, 20 alpha-dihydroxy-18,20-cyclopregn-4-en-3-one (Ia) took place upon electron impact. Deuterium labeling demonstrated that the first steps of mass spectral fragmentation of Ia were the rearrangement to IIa and the oxidative cleavage to 3,18,20-trioxo-4-pregnene (IVa).
mesh_terms: D000736:Androstenes / Q000138:chemical synthesis* / Q000378:metabolism; D000818:Animals; D003525:Cyclosteroids / Q000138:chemical synthesis* / Q000378:metabolism; D005260:Female; D007668:Kidney / Q000378:metabolism; D013058:Mass Spectrometry; D011817:Rabbits; D051381:Rats; D011987:Receptors, Steroid / Q000378:metabolism; D014599:Uterus / Q000378:metabolism
chemical_list: D000736:Androstenes; D003525:Cyclosteroids; D011987:Receptors, Steroid