Thiourea-enhanced flavin photooxidation of benzyl alcohol

被引:77
作者
Svoboda, Jiri [1 ]
Schmaderer, Harald [1 ]
Koenig, Burkhard [1 ]
机构
[1] Univ Regensburg, Inst Organ Chem, D-93040 Regensburg, Germany
关键词
flavins; photooxidation; redox chemistry; thiourea;
D O I
10.1002/chem.200701319
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Upon irradiation, flavin oxidises 4-methoxybenzyl alcohol to the corresponding aldehyde using aerial 02 as the terminal oxidant. We have observed that this reaction is significantly accelerated by the presence of thiourea. A series of thiourea-functionalised flavins has been prepared from flavin isothiocyanates and their photocatalytic efficiencies have been monitored by NMR. The alcohol photooxidation proceeds rapidly and cleanly with high turnover numbers of up to 580, exceeding previously reported performances. A likely mechanistic rationale for the more than 30-fold acceleration of the photo-redox reaction by thiourea has been derived from spectroscopic, electrochemical, and kinetic studies. Thus, thiourea acts as an electron-transfer mediator for the initial photooxidation of 4-methoxybenzyl alcohol by the excited flavins. This mechanism has similarities to electron-relay mechanisms in flavoenzymes, for which cysteine sulfenic acid intermediates are proposed. The observation that thiourea mediates flavin photo-redox processes is valuable for the design of more sophisticated photocatalysts based on Nature's best redox chromophore.
引用
收藏
页码:1854 / 1865
页数:12
相关论文
共 111 条
[81]   Electrostatics of cell membrane recognition: Structure and activity of neutral and cationic rigid push-pull rods in isoelectric, anionic, and polarized lipid bilayer membranes [J].
Sakai, N ;
Gerard, D ;
Matile, S .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2001, 123 (11) :2517-2524
[82]   REINVESTIGATION OF THE BAMBERGER-HAM PHENAZINE SYNTHESIS - LIMITATION [J].
SAWHNEY, SN ;
BOYKIN, DW .
JOURNAL OF HETEROCYCLIC CHEMISTRY, 1979, 16 (02) :397-400
[83]   FREE-ENERGY RELATIONSHIPS FOR REVERSIBLE AND IRREVERSIBLE ELECTRON-TRANSFER PROCESSES [J].
SCANDOLA, F ;
BALZANI, V ;
SCHUSTER, GB .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1981, 103 (10) :2519-2523
[84]   γ-Amino-substituted analogues of 1-[(S)-2,4-diaminobutanoyl]piperidine as highly potent and selective dipeptidyl peptidase II inhibitors [J].
Senten, K ;
Van der Veken, P ;
De Meester, I ;
Lambeir, AM ;
Scharpé, S ;
Haemers, A ;
Augustyns, K .
JOURNAL OF MEDICINAL CHEMISTRY, 2004, 47 (11) :2906-2916
[85]   FLAVIN-ZR-4+ COMPLEX AS OXIDATION CATALYST [J].
SHINKAI, S ;
ISHIKAWA, Y ;
MANABE, O .
CHEMISTRY LETTERS, 1982, (06) :809-812
[86]   CO-ENZYME MODELS .31. EFFICIENT TRAPPING OF TRANSIENT THIAZOLIUM ALDEHYDE ADDUCTS (ACTIVE ALDEHYDES) BY INTRAMOLECULAR AND QUASI-INTRAMOLECULAR FLAVINS - FLAVIN THIAMIN BISCOENZYME [J].
SHINKAI, S ;
YAMASHITA, T ;
KUSANO, Y ;
MANABE, O .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1982, 104 (02) :563-568
[87]   COENZYME MODELS .41. ON THE UNUSUAL REACTIVITIES OF N(5)-HYDROGEN-BONDED FLAVIN - AN APPROACH TO REGIOSPECIFIC FLAVIN ACTIVATION THROUGH HYDROGEN-BONDING [J].
SHINKAI, S ;
HONDA, N ;
ISHIKAWA, Y ;
MANABE, O .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1985, 107 (22) :6286-6292
[88]   Exploring the mechnisms of molecular recognition by flavins [J].
Singh, R ;
Geetanjali ;
Babu, CR .
CHEMISTRY & BIODIVERSITY, 2005, 2 (04) :429-446
[89]   MECHANISMS OF ISOALLOXAZINE (FLAVINE) HYDROLYSIS [J].
SMITH, SB ;
BRUICE, TC .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1975, 97 (10) :2875-2881
[90]   [3.3]ISOALLOXAZINOPHANES AND ARENE-BRIDGED BIS(ISOALLOXAZINES) - SYNTHESES, CHARACTERIZATIONS AND PROPERTIES RELATED TO INTRAMOLECULAR INTERACTIONS [J].
STAAB, HA ;
KIRSCH, P ;
ZIPPLIES, MF ;
WEINGES, A ;
KRIEGER, C .
CHEMISCHE BERICHTE, 1994, 127 (09) :1653-1665