Temperature Dependence of the Reduction of Phthalic Thioanhydrides by NaBH4: Competition between 3-Hydroxythiolactone and Phthalide Formation
作者:Iwona Polec、Laurence Lutsen、Dirk Vanderzande、Jan Gelan
DOI:10.1002/1099-0690(200203)2002:6<1033::aid-ejoc1033>3.0.co;2-s
日期:2002.3
The reduction of phthalic thioanhydrides with NaBH4 at between 0 and −20 °C leads to the selective formation of 3-hydroxy-2-thiophthalides, whereas higher temperatures favour the formation of the corresponding phthalide derivatives. A mechanism is proposed that can explain these observations. Kinetic control at low temperatures leads to an improved stability of the intermediate alkoxide, thus allowing
在 0 到 -20 °C 之间用 NaBH4 还原邻苯二甲酸硫酐导致选择性形成 3-羟基-2-硫代苯甲醚,而较高的温度有利于相应苯酞衍生物的形成。提出了一种可以解释这些观察结果的机制。低温下的动力学控制导致中间体醇盐的稳定性提高,从而允许在反应混合物的后续酸化后分离 γ-羟基硫代内酯。以这种方式避免了热力学有利的邻苯二甲酸酯衍生物的形成。用 AcOH/57% HI 水溶液进一步还原 γ-羟基硫内酯产生 2-硫代苯酞,这是导电聚合物的有用前体。(© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)