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Inicio » Actividades I+D > Publicaciones 2001 > Rearrangement of 18-Iodo- and 20-Iodopre...
artículo con referato
"Rearrangement of 18-Iodo- and 20-Iodopregnanes Mediated by Iodosyl Derivatives"
D. Nicoletti, A.A. Ghini, R.F. Baggio, M.T. Garland and G. Burton
J. Chem. Soc., Perkin Trans. 1 13 (2001) 1511-1517
Conversion of 20-acetoxy-18-iodopregn-4-en-3-one 1 to the 18-iodosyl derivative by MCPBA resulted in a Wagner-Meerwein-type rearrangement with regioselective migration of the C13-C17 bond to give, in high yield, an abeo-pregnane in which C-18 was incorporated into ring D. The rearranged steroid was epoxidized in situ yielding a mixture of β and α 13,14-epoxides (3 and 4) which were characterized spectroscopically and by X-ray crystallography. When (20R)-20-iodopregn-4-en-3-one 9a was used as substrate, regioselective migration of the C16-C17 bond gave the D-homoandrostane with incorporation of C-20 into ring D in up to 95% yield. The 20S epimer 9b however, gave a mixture of substitution and rearrangement products. The crystal structures of the deacetylated β-epoxide 3 (5), the methanolysis product of α-epoxide 4 (7) and 20-iodopregnanes 9a and 9b are reported.
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