Synthesis, properties, and oxidizing function of 6-substituted 7,9-dimethylcyclohepta[b]pyrimido[5,4-d]pyrrole-8(7H),10(9H)-dionylium tetrafluoroborates

Novel Synthesis, Properties, and Oxidizing Ability of 11,13-Disubstituted 3,8-Methanocycloundeca[8,9-b]pyrimido[5,4-d]-furan-12(11H),14(13H)-dionylium Tetrafluoroborates

“…The E 1 red of 11a − c are more positive by 0.15, 0.17, and 0.13 V than those of 2a − c , respectively. The irreversible nature is probably due to the formation of a radical species and its dimerization, as reported to be a typical property of uracil-annulated heteroazulenylium ions. − The p K R+ values of 11a − c are larger than that of 2a ; however, the first reduction potentials ( E 1 red ) of 11a − c are more positive than that of 2a . This feature is rationalized by the elongated π-conjugation of 11a − c as compared with 2a − c .…”

“…Compound 17a is oxidized by DDQ to regenerate 11a · BF 4 - in good yield. Previously, we have reported that the reaction of 2a · BF 4 - or 3a − c · BF 4 - with NaBH 4 proceeded at the 1-, 3-, and 5-positions to afford a mixture of three regio-isomers. − On the other hand, the reaction of 11a · BF 4 - proceeded at only the 9-position to afford single isomer 17a , and other regioisomers, such as 18a , are not obtained. There is a well-known tendency for double bond fixation in the methano[11]annulene system to favor a cycloheptatriene system in the compound 17a predominantly over a 1,6-dimethylenecyclohepta-2,4-diene system in compound 18a .…”

“…Reactivity of 11a. The reaction site of 2a · BF 4 - and 3a − c · BF 4 - with some nucleophiles depends on the nucleophiles and heteroatom on the cations. − Thus, the reactions of 11a · BF 4 - with some nucleophiles were carried out. Reduction of 11a · BF 4 - with NaBH 4 in CH 3 CN afforded compound 17a in good yield (Scheme ).…”

“…Autorecycling Oxidation of Alcohols and Amines. Compounds 2a · BF 4 - and 3a − c · BF 4 - undergo autorecycling oxidation toward some alcohols under photoirradiation. − In this context and in a search for oxidizing ability of 11a · BF 4 - , we examined the oxidation of some alcohols and amines by using 11a · BF 4 - under aerobic and photoirradiation conditions (RPR-100, 350 nm lamps). Although alcohols and cyclohexylamine were not oxidized by 11a · BF 4 - , we found that compound 11a · BF 4 - has oxidizing ability toward benzylamine and 1- phenylethylamine to give benzaldehyde and acetophenone.…”

Synthesis, Properties, and Oxidizing Ability of 9,11-Dimethylbenzocyclohepta[6,7-b]pyrimido[5,4-d]furan- 10(9H),12(11H)-dionylium Tetrafluoroborate

“…We have recently reported the oxidative cyclization of heptafulvenes 4a,b by using DDQ to afford tropylium ions annulated with furo[2,3- d ]pyrimidine-1(2 H ),3(4 H )-dione, 5a,b · BF 4 - . In this context, the synthesis, properties, and reactivity of 6a − c · BF 4 - 8b,c and 7a,b were investigated as well. Furthermore, novel photoinduced autorecycling oxidizing reactions of 5a · BF 4 - 8a and 6a − c · BF 4 - 8b,c toward some alcohols to give the corresponding carbonyl compounds are studied.…”