Novel synthesis, properties, and NAD+-NADH type redox ability of 1,3-dimethylcyclohepta[4,5]pyrrolo[2,3-d]pyrimidine-2,4(1,3H)-dionylium ions annulated with additional pyrrolo[2,3-d]pyrimidine-1,3(2,4H)-dione and furan analogue, and their hydride adducts

A convenient preparation of novel cations 11a,b(+center dot)BF(4) and 12a,b(+center dot)BF(4), which are derived from annulation of the 1,3-dimethyleyclohepta[4,5]pyrrolo[2,3-d]pyrimidine-2,4(1,3H)-dionylium ion with additional pyrrolo[2,3-d]pyrimidine-1,3(2,4H)-dione and a furan analogue, was accomplished by a novel oxidative cyclization of 1,7-dihydro-7-[1',3'-dimethyl-2',4'(1',3'H)-dioxo-6'-(phenylamino)-pyrimidin-5'-yll-1,3-dimethyl-10-phenylcyclohepta[4,5] pyrrolo [2,3-d] pyrimidine-2,4(1,3H)-dione 9 and its furan-analogue by using DDQ or photoirradiation under aerobic conditions. Structural characteristics of 11a,b(+) and 12a,b(+) were clarified on inspection of the LTV-vis and NMR spectral data as well as X-ray crystal analyses. The stability of cations 11a,b' and 12a,b' is expressed by the pK(R+), values that were determined spectrophotometrically to be 10.7-12.6. The electrochemical reduction of 11a,b(+center dot)BF(4)(-) and 12a,b(+center dot)BF(4)(-) exhibited reduction potential at -0.93 to - 1.00 (V vs Ag/AgNO3). The first reduction potential of 11a(+) was reversible due to steric hindrance of two phenyl groups. The photoinduced oxidation reaction of 11a,b(+center dot)BF(4) and 12a,b(+center dot)BF(4) toward some amines under aerobic conditions was carried out to give the corresponding imines (isolated by converting to the corresponding 2,4-dinitrophenylhydrazones) with the recycling numbers of 0.6-30.3. Furthermore, as an example of the NAD(+)-NADH models, the reduction of a pyruvate analogue and some carbonyl compounds with the hydride-adduct of 11a(+center dot)BF(4) was accomplished for the first time to give the corresponding alcohol derivatives.