| 摘要 |
<p>(A) Separation of the cis and trans isomers of (I). R1,2 = lower alkyl; or NR1R2 = heterocyclyl, R3 = lower alkyl. (B) Conversion of the cis isomer into a mixt. of cis and trans. As analgesics free from undesirable secondary effects, espec. the trans isomer. A soln. of the mixed isomers in aq. HCl, at pH 2.5-3.5, is treated with 15-40% aq. ZnCl2 to ppt. a Zn complex of the cis isomer; this is separated and treated with conc. NH4OH-CHCl3 to recover the cis-base, whilst the trans-base is obtained from the soln. by basifn. to pH 8.5-9.5 and solvent extn. The cis isomer is converted into a cis-trans mixt. by heating with dicyclo-hexylamine, hydroquinone or alpha-naphthylamine at 150-160 deg.C, under N2, for ca. 3 hrs.</p> |
