Both trans and cis isomers
of 4-amino-3-halogenobut-2-enoic acid have been prepared as potential irreversible
inhibitors of the enzyme GABA- transaminase. trans-Addition of HX to
4-chlorobut-2-ynoic acid and subsequent amination gave the trans isomers (2; X
= Cl, Br, I), while the key step in the synthesis of
the cis isomers (3; X = Cl, Br) was the isomerization
to cis-4-bromo-3-halogenobut-2-enoic acids during allylic bromination. The
stereochemical assignments are supported by 1H and 13C
n.m.r. spectral data. A convenient preparation of cis-4- aminobut-2-enoic acid
by reduction of the bromo derivative is described, as well as the synthesis of
4-phthalimidobut-2-ynoic acid which is suitable for preparing radiolabelled
GABA of high specific activity.
反式和顺式异构体
4-amino-3-halogenobut-2-enoic acid 的反式和顺式异构体都被制备成潜在的不可逆
抑制剂。
4-chlorobut-2-ynoic acid 并随后进行胺化,可得到反式异构体(2;X
=Cl、Br、I),而合成顺式异构体(3;X
而合成顺式异构体(3;X = Cl、Br)的关键步骤是异构化
而合成顺式异构体(3;X = Cl、Br)的关键步骤是在烯丙基溴化过程中异构化成顺式-4-溴-3-卤代丁烯-2-酸。这些
1H 和 13C
n.m.r. 光谱数据的支持。顺式-4-氨基丁-2-烯酸的简便制备方法
的简便制备方法,以及 4-邻苯二甲酰亚胺丁-2-烯酸的合成方法。
4- 邻苯二甲酰亚胺丁-2-炔酸,它适用于制备放射性标记的
高特异性 GABA。