Novel Synthesis and Oxidizing Ability of Tropylium Ions Annulated with Two 2,4-Dimethylfuro[2,3-d]pyrimidine-1(2H),3(4H)-diones

详细信息    查看全文

• 作者：Shin-ichi Naya ; Takeshi Tokunaka ; and Makoto Nitta
• 刊名：Journal of Organic Chemistry
• 出版年：2004
• 出版时间：July 9, 2004
• 年：2004
• 卷：69
• 期：14
• 页码：4732 - 4740
• 全文大小：250K
• 年卷期：v.69,no.14(July 9, 2004)
• ISSN：1520-6904

文摘

Convenient preparation of novel tropylium ions annulated with two 2,4-dimethylfuro[2,3-d]pyrimidine-1(2H),3(4H)-diones, 12a⁺·BF₄^- and 12b⁺·BF₄^-, consists of a reaction of 2-methoxytroponewith dimethylbarbituric acid to give 7,9-dimethyl-3-[1',3'-dimethyl-2'(1'H),4'(3'H),6'(5'H)-trioxopyrimidin-5'-ylidene]cyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dione 8 and the following oxidative cyclization by using DDQ or photoirradiation under aerobic conditions. On the basis of theMO calculations, the selectivity of two types of oxidative cyclization reactions of 8 was rationalized.X-ray crystal analyses and MO calculations were carried out to clarify the structural characteristicsof 12a⁺·BF₄^- and 12b⁺·BF₄^-. The stability of cations 12a⁺ and 12b⁺ is expressed by the pK_R⁺ valueswhich were determined spectrophotometrically as 8.8 and 8.6. The electrochemical reduction of12a⁺ and 12b⁺ exhibited reduction potential at -0.63 and -0.62 (V vs Ag/AgNO₃), respectively.Reactions of 12a⁺·BF₄^- and 12b⁺·BF₄^- with some nucleophiles, hydride and diethylamine, werecarried out to clarify that the reactivity of 12a⁺·BF₄^- and 12b⁺·BF₄^- was substantially dependenton the annulating position. The oxidizing ability of 12a⁺·BF₄^- and 12b⁺·BF₄^- toward alcohols andamines in the autorecycling process was demonstrated as well.