Synthesis, Structure, and Keto-Enol Tautomerism of 3-R1-5,5-R2,R2-6-R3-2,3,5,6-Tetrahydropyran-2,4-diones
作者:V. V. Shchepin、M. I. Kodess、Yu. Kh. Sazhneva、N. Yu. Russkikh
DOI:10.1007/s11176-005-0477-6
日期:2005.10
Ethyl esters of 2,4-dibromo-2-R1-4-R2-3-oxopentanoic and -hexanoic acids react with zinc and aliphatic or aromatic aldehydes under the conditions of the Reformatskii reaction to give 3-R1-5,5-R2, R2-6-R3-2,3,5,6-tetrahydropyran-2,4-diones, which are obtained in three forms: keto, enol with enolization of the keto group, and enol with enolization of the ester group. The keto form is isolated by crystallization
2,4-二溴-2-R 1 -4-R 2 -3-氧戊酸和-己酸的乙酯在Reformatskii反应的条件下与锌和脂族或芳族醛反应生成3-R 1 -5, 5-R 2,R 2 -6-R 3 -2,3,5,6-四氢吡喃-2,4-二酮以三种形式获得:酮基,带有酮基的烯醇化烯醇和带有烯化的烯醇酯基团。通过结晶从CCl 4和石油醚的混合物中分离出酮形式。第一种烯醇形式,来自MeOH,EtOH和极性非质子溶剂;第二种烯醇形式,来自CHCl 3。第二种烯醇形式在DMSO中被氧化以形成在杂环的3-位上含有羟基的酮化合物。