| 摘要 |
<p>Conventionally produced triforine (I) consists of 3 optical forms, differing in fungicidal activity viz(-)(-)>> mes >(I) (-), in the ratio 25:50:25. The racemate ((-)(-), (+)(-)) is generally more sol. than the meso and is pref. extd. e.g. with 10% H2O in Me2Co or with DMF, giving (I) with >60, pref. 70-95% racemate. Alternatively the (-)(-) form may be synthesised by: (a) condensing piperazine with (+)(-)- CCl3CHClNHCHO (II), (b) resolving e.g. via. the l(+)-tartrate, (c) basifying (NaOH) to isolate the (-)-inter. (d) condensing with another mole of (II) (e) fractionation by solvent extn. as above, to give the pure (-)(-) and (+)(-) forms. Meso form, obtd. by either route, may be isomerised by heating at 40-110 degrees C in a solvent e.g. DMF and recycling.</p> |
