Dye-sensitizedphoto-oxygenation of L-tryptophan (1) has been studied at various pH and in various buffers. Disappearance of 1 in both acetate and phosphate buffers was rapid at higher pH. The tricyclic hydroperoxide (8) was the sole product in the oxidation of 1 over the range pH 3.6–7.1 in acetate and phosphate buffers. However, the oxidation of 1 in alkaline phosphate and borate buffers (pH 7.7–8
已在各种pH和各种缓冲液中研究了L-色氨酸(1)的染料敏化光氧合。在较高的pH值下,乙酸盐和磷酸盐缓冲液中1的消失迅速。三环过氧化氢(8)是在乙酸盐和磷酸盐缓冲液中pH 3.6至7.1范围内1氧化的唯一产物。然而,在碱性磷酸盐和硼酸盐缓冲液(pH 7.7–8.4)中1的氧化产生了5-羟基甲酰基kynurenine(10)作为主要产物。中间体3a,5-二羟基吡咯并吲哚(16)可以由三环氢过氧化物(8)通过醌亚胺(15)形成。通过立即用NaBH 4还原反应混合物,以高收率获得了NaCl 3)。在碱性介质中16的分子氧(基态)氧化提供10。色胺(17a)的相似氧化和还原得到3a,5-二羟基吡咯并吲哚(18b),其未进一步氧化为5-羟基甲酰基炔脲。另一方面,在Na 2 CO 3 -AcOH(pH 7)中对染料1进行染料增感光氧合,得到甲酰基炔尿氨酸(3)作为主要产物。