Chromic acid oxidation in the synthesis of uronic acids. Use of the O-levulinoyl group to minimize acyl migration
作者:Rabindra N. Rej、John N. Glushka、Warren Chew、Arthur S. Perlin
DOI:10.1016/0008-6215(89)84092-3
日期:1989.6
include levulinoyl at O-5 of acylic and furanose derivatives, and both eq and ax O-4 of pyranose derivatives. It is also shown that, because of the acidity of the Jones reagent, use of the O -levulinoyl group, in combination with a primary p -anisyldiphenylmethyl substituent, permits sequential rapid hydrolysis of the latter and oxidation of the newly exposed alcohol group, which favors high overall yields
摘要在部分酰化的糖衍生物的铬酸盐氧化反应中形成相应的糖醛酸时,酰基向伯醇基的迁移是干扰的常见原因。与更常用的酯取代基相比,在用琼斯试剂(铬硫酸)氧化的过程中,O-乙酰丙酰基的迁移率要低得多。这里描述的例子包括酰基和呋喃糖衍生物的O-5处的乙酰丙酰基,以及吡喃糖衍生物的eq Ox和ax O-4。还表明,由于琼斯试剂的酸性,将O-乙酰丙酰基与伯对-茴香基二苯基甲基取代基结合使用,可使后者顺序快速水解,并使新暴露的醇基氧化。有利于高总产。与它在这些氧化反应中的固定性相反,当乙酰丙酰基在醛糖基溴的O-2上时,它与O-乙酰基一样迅速地参与1,2-原酸酯的形成。d-吡喃葡萄糖苷甲基的任一异构体的2,3,4,6-四乙酸酯被铬酸在5:1乙酸-水中的氧化,以中等收率氧化为糖醛酸。