548475-54-3Relevant academic research and scientific papers
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.
Novel synthesis and properties of 7,9-dimethylcyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dionylium tetrafluoroborate: Autorecycling oxidation of some alcohols under photo-irradiation
Naya, Shin-Ichi,Miyama, Hisashi,Yasu, Kenji,Takayasu, Tohru,Nitta, Makoto
, p. 1811 - 1821 (2007/10/03)
Three-step reactions starting from 2-chlorotropone with barbituric acid afforded novel 7,9-dimethylcyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dionylium tetrafluoroborate (9·BF4-), which is the isoelectronic compound of the 5-ethyl-3-methyllumiflavinium ion. The stability of cation 9 is expressed by the pKR+ value, which was determined spectrophotometrically, as ca. 6.0. The electrochemical reduction of 9 exhibited low reduction potential at -0.58 (V vs Ag/AgNO3), upon cyclic voltammetry (CV). In a search for the reactivity, reactions of 9·BF4- with some nucleophiles, hydroxide, hydride, amines, thiols, and methanol, were carried out to exhibit that the introduction of nucleophiles is dependent on the nucleophile itself. The photo-induced oxidation reactions of some alcohols catalyzed by 9·BF4- under aerobic conditions were carried out to give the corresponding carbonyl compounds in more than 100% yield [based on compound 9·BF4-], suggesting the oxidizing function of 9·BF4- toward alcohols in the autorecycling process. The UV-vis and fluorescence spectra of 9 were studied to suggest the electron transfer from alcohols to the excited 9.
