作者:S. Ravi、K. M. Mathew、D. Padmanabhan、V. K. P. Unny、N. Sivaprasad
DOI:10.1002/jlcr.1048
日期:2006.3.30
Condensation of thiourea 1 with diethyl malonate 2 in the presence of sodium methoxide furnished 4,6-dihydroxy-2-mercaptopyrimidine 3. Compound 3 on methylation with diazomethane followed by oxidation with H5IO6/CrO3 in ethyl acetate gave 4,6-dimethoxy-2-methylsulphonylpyrimidine 5. Compound 5 on condensation with 2-mercapto-6-chlorobenzoic acid in the presence of a phase transfer catalyst, tetrabutylammonium bromide and sodium carbonate gave the title compound – pyrithiobac-sodium 6 with an overall yield of > 35% starting from thiourea. Following the above standardized procedure, using [14C]-thiourea in lieu of thiourea, 14C labelled product 6, was synthesized with an overall radiochemical yield > 30% (with respect to [14C]-thiourea) for further evaluations of environmental fate of 6, in soils and plants. Copyright © 2006 John Wiley & Sons, Ltd.
这是一段有关农药吡硫酯钠合成路线的描述。主要步骤如下:
1. 硫脲(1)与丙二酸二乙酯(2)在甲醇钠存在下缩合得到4,6-二羟基-2-巯基嘧啶(3)。
2. 化合物3经重氮甲烷甲基化,然后用乙酸乙酯中的H5IO6/CrO3氧化得到4,6-二甲氧基-2-甲基磺酰基嘧啶(5)。
3. 化合物5与2-巯基-6-氯苯甲酸在相转移催化剂四丁基溴化铵和碳酸钠存在下缩合,得到目标产物吡硫酯钠(6),从硫脲开始的总收率大于35%。
4. 按照上述标准程序,用[14C]-硫脲代替硫脲,合成了14C标记的产物6,总放射化学收率大于30%(相对于[14C]-硫脲),用于进一步评估化合物6在土壤和植物中的环境归趋。
版权所有 © 2006 John Wiley & Sons, Ltd.