548475-54-3Relevant articles and documents
Novel synthesis and oxidizing ability of tropylium ions annulated with two 2,4-dimethylfuro[2,3-d]pyrimidine-1(2H),3(4H)-diones
Naya, Shin-Ichi,Tokunaka, Takeshi,Nitta, Makoto
, p. 4732 - 4740 (2007/10/03)
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-methoxytropone with 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 the MO 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 characteristics of 12a+·BF4- and 12b+· BF4-. The stability of cations 12a+ and 12b+ is expressed by the pKR+ values which were determined spectrophotometrically as 8.8 and 8.6. The electrochemical reduction of 12a+ and 12b+ exhibited reduction potential at -0.63 and -0.62 (V vs Ag/AgNO3), respectively. Reactions of 12 a+·BF4- and 12b+· BF4- with some nucleophiles, hydride and diethylamine, were carried out to clarify that the reactivity of 12a+· BF4- and 12b+·BF4- was substantially dependent on the annulating position. The oxidizing ability of 12a+·BF4- and 12b+-BF 4- toward alcohols and amines in the autorecycling process was demonstrated as well.
