Racemic modifications of the pyridoxal-like ansa compounds such as 15-formyl-14-hydroxy-2,8-dithia[9](2,5)pyridinophanes prepared as a pontential catalyst for stereospecific nonenzymatic reactions were optically resolved through formation of Schiff bases by treatment with amino sugar derivatives or amino acids. Resolutions with the amino sugar derivatives were ascribable to the difference of the solubilities of the diastereomeric Schiff bases, whereas those with the amino acids resulted from the difference of the reaction rates for the formation of the diastereomeric Schiff bases. As the amino sugar resolving agents, 3-amino-3-deoxy-1,2:5,6-di-O-isopropylidene-β-d-idofuranose and the corresponding α-d-glucofuranose isomer were employed and gave (R)- and (S)-pyridoxal-like pyridinophanes, respectively. On the other hand, chiral valine was the most efficient resolving agent among the amino acid tested and the presence of half equimolar Fe3+ markedly increased the optical purities of the products. Employment of (S)-valine gave (R)-pyridinophanes in excess and vice versa.
15- 甲酰基-1
4-羟基-2,8-二
硫杂[9](2,5)
吡啶烷等
吡哆
醛类安息香酸化合物的外消旋修饰被制备成立体特异性非酶反应的潜在催化剂,通过
氨基糖衍
生物或
氨基酸处理形成希夫碱,从而在光学上解决了外消旋修饰问题。用
氨基糖衍
生物进行解析是因为非对映异构体希夫碱的溶解度不同,而用
氨基酸进行解析则是因为形成非对映异构体希夫碱的反应速率不同。采用 3-
氨基-3-脱氧-1,2:5,6-二-O-异亚丙基-β-d-异
呋喃糖和相应的α-d-
葡萄糖呋喃糖异构体作为
氨基糖分解剂,分别得到了(R)-和(S)-
吡哆醛样
吡啶烷。另一方面,在所测试的
氨基酸中,手性缬
氨酸是最有效的分辨剂,半等摩尔 Fe3+ 的存在显著提高了产物的光学纯度。使用(S)-缬
氨酸可以得到过量的(R)-
吡啶烷,反之亦然。