Rearrangement of 18-iodo- and 20-iodopregnanes mediated by iodosyl derivatives
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...
Guardado en:
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2001
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_14727781_v1_n13_p1511_Nicoletti http://hdl.handle.net/20.500.12110/paper_14727781_v1_n13_p1511_Nicoletti |
| Aporte de: |
| Sumario: | 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 9 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 9 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 9 and 9 are reported. © 2001 The Royal Society of Chemistry. |
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