TY - JOUR
T1 - Acid-catalysed reduction of flavin analogues by an NADH model compound, 10-methyl-9,10-dihydroacridine and cis-dialkylcobalt(III) complexes
AU - Fukuzumi, Shunichi
AU - Kuroda, Sadaki
AU - Goto, Tatsushi
AU - Ishikawa, Kunio
AU - Tanaka, Toshio
PY - 1989
Y1 - 1989
N2 - An acid-stable NADH model compound, 10-methyl-9,10-dihydroacridine (AcrH2) (3), and cis-dialkylcobalt(III) complexes, cis-[R 2Co(bipy)2]+ (R = Me, Et; bipy = 2,2′-bipyridine), can reduce flavin analogues {Fl: 3-methyl-10- phenylbenzo[g]pteridine-2(1H),4(3H)-dione (1) and riboflavin (2)}, efficiently in the presence of perchloric acid (HClO4) in acetonitrile (MeCN) at 298 K to yield the corresponding dihydroflavin radical cations (FlH 2+.). Essentially, no reaction occurs in the absence of HClO4 under the same conditions. The radical cations (FlH 2+.) formed are very stable to oxygen in the presence of HClO4 in MeCN. Large primary kinetic isotope effects [k H/kD 9.6 ± 0.8 and 9.9 ± 0.8 for (1) and (2), respectively] have been observed for the formation of FlH2 +., indicating that hydride transfer from AcrH2 to the protonated flavins (FlH+) to give the dihydroflavins (FlH 2) is followed by fast comproportionation between FlH2 and FlH+ to yield FlH2+. in the presence of HClO4 in MeCN. The reaction mechanisms of hydride transfer from AcrH2 to FlH+ are compared with the acid-catalysed electron-transfer reactions from cis-[R2Co(bipy)2] + to FlH+.
AB - An acid-stable NADH model compound, 10-methyl-9,10-dihydroacridine (AcrH2) (3), and cis-dialkylcobalt(III) complexes, cis-[R 2Co(bipy)2]+ (R = Me, Et; bipy = 2,2′-bipyridine), can reduce flavin analogues {Fl: 3-methyl-10- phenylbenzo[g]pteridine-2(1H),4(3H)-dione (1) and riboflavin (2)}, efficiently in the presence of perchloric acid (HClO4) in acetonitrile (MeCN) at 298 K to yield the corresponding dihydroflavin radical cations (FlH 2+.). Essentially, no reaction occurs in the absence of HClO4 under the same conditions. The radical cations (FlH 2+.) formed are very stable to oxygen in the presence of HClO4 in MeCN. Large primary kinetic isotope effects [k H/kD 9.6 ± 0.8 and 9.9 ± 0.8 for (1) and (2), respectively] have been observed for the formation of FlH2 +., indicating that hydride transfer from AcrH2 to the protonated flavins (FlH+) to give the dihydroflavins (FlH 2) is followed by fast comproportionation between FlH2 and FlH+ to yield FlH2+. in the presence of HClO4 in MeCN. The reaction mechanisms of hydride transfer from AcrH2 to FlH+ are compared with the acid-catalysed electron-transfer reactions from cis-[R2Co(bipy)2] + to FlH+.
UR - http://www.scopus.com/inward/record.url?scp=37049067766&partnerID=8YFLogxK
U2 - 10.1039/p29890001047
DO - 10.1039/p29890001047
M3 - Article
AN - SCOPUS:37049067766
SN - 1472-779X
SP - 1047
EP - 1053
JO - Journal of the Chemical Society. Perkin Transactions 2
JF - Journal of the Chemical Society. Perkin Transactions 2
IS - 8
ER -