Portal de Periódicos da CAPES

On the closure of the 4,5‐oxygen bridge in morphinans 1 H and 13 C NMR spectroscopy of brominated intermediates. (Chemistry of opium alkaloids, Part IX)

1978; Royal Netherlands Chemical Society; Volume: 97; Issue: 2 Linguagem: Inglês

10.1002/recl.19780970202

1878-7096

C. Olieman, L. Maat, H. C. Beyerman,

Alkaloids: synthesis and pharmacology

Abstract 1 H and 13 C Nuclear magnetic resonance spectra of brominated dihydrothebainones, needed for the closure of the oxygen bridge of morphinans to form morphine derivatives, were studied. Bromination of (‐)‐dihydrothebainone (1) yielded successively 1‐bromo‐, 1,7α‐dibromo‐, and 1,5β,7α‐tribromo‐dihydrothebainone (2,3,4) . 1‐Bromo‐ O 4 ‐methyldihydrothebainone (12) gave, after bromination, a stable crystalline l,5β,7α‐tribromo derivative (15) . A 5β,7α‐dibromo derivative (9) was formed also starting with l‐methyldihydrothebainone (7) . Closure of the oxygen bridge in 1,5β,7α‐tribromodihydrothebainone (4) in boiling ethanol, yields an equilibrium mixture of 1,7β‐ and 1,7β‐dibromodihydrothebainone ( 5:6 , ∼ 35 : 65). 5β,7α‐Dibromo‐l‐methyldihydrothebainone (9) gave the same result. 13 C NMR spectra of the model compounds cyclohexanone, 2‐bromo‐, 2,2‐dibromo‐, cis‐ and trans‐2,6‐dibromo‐cyclohexanone were studied.