Photochemische Reaktionen 42. Mitteilung [1]. Photoisomerisierung von α, β-Epoxyketonen II Der sterische Verlauf der Umlagerung von 3-Oxo-4, 5-oxido-Steroiden |
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Authors: | H Wehrli C Lehmann T Iizuka K Schaffner O Jeger |
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Abstract: | The photorearrangement previously described 3] of saturated and Δ1-unsaturated 3-oxo-4,5-epoxy-10β-steroids to 3,5-dioxo-10(5 →4)-abeo compounds proceeds most likely via a radical 1,2-alkyl shift (Chart 1). The similar rearrangements of the related 10α-epoxyketone 10 and the 4-methyl-epoxyketones 13 , 15 , 16 , 20 and 21 to the corresponding 3,5-diketones occurred without epimerization at the migrating carbon atom (C-10) and the site of substitution (C-4) (Chart 3). The stereochemical control of the rearrangement is in agreement with the earlier proposed mechanism of a concerted alkyl radical shift in these alicyclic systems. |
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