6972-71-0Relevant academic research and scientific papers
Synthesis of symmetric dinitro-functionalised troeger's base analogues
Bhuiyan, M Delower H,Mahon, Andrew B.,Jensen, Paul,Clegg, Jack K.,Try, Andrew C.
supporting information; experimental part, p. 687 - 698 (2009/07/17)
The synthesis of six new examples of 2,8-dinitro-substituted Troeger's base analogues are reported, together with the first examples of 1,7-, 3,9- and 4,10-dinitro Troeger's base analogues and the first example of a tetranitro Troeger's base compound. Several of these dinitro compounds lack substituents at the 2- and 8-positions and therefore provide further examples of Troeger's base analogues derived from anilines lacking a para substituent.
Concise total synthesis of
Buszek, Keith R.,Brown, Neil,Luo, Diheng
supporting information; experimental part, p. 201 - 204 (2009/06/20)
An efficient nine-step total synthesis of the annulated indole natural products.
Recognition properties of flavin analogues with bile acid-based receptors: Role of steric effects in hydrogen bond based molecular recognition
Chattopadhyay, Prosenjit,Nagpal, Rekha,Pandey, Pramod S.
, p. 216 - 222 (2008/09/18)
The recognition properties of 7,8-dimethyl flavin analogues by bile acid-based receptors that contain 2,6-diaminopyridine and the dioctylamide of 2,6-diaminopyridine in CHCl3 were determined. The results show that the bile acid-based receptors bind 7,8-dimethyl flavin analogues less effectively as compared to 7,8-unsubstituted flavins reported earlier, which is contrary to the known fact that the association constants increase with increasing electron-donating capacity of the substituents at the 7 and 8 positions of the flavin analogues. CSIRO 2008.
Thiourea-enhanced flavin photooxidation of benzyl alcohol
Svoboda, Jiri,Schmaderer, Harald,Koenig, Burkhard
supporting information; experimental part, p. 1854 - 1865 (2009/04/06)
Upon irradiation, flavin oxidises 4-methoxybenzyl alcohol to the corresponding aldehyde using aerial O2 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.
Improved synthesis of thromboxane A2 receptor antagonists with a dibenzoxepin ring system
Sugaya,Kato,Sakaguchi,Tomioka
, p. 1257 - 1262 (2007/10/02)
Two derivatives of sodium (E)-11-[2-(1-benzimidazolyl)ethylidene]11-oxo-6,11-dihydrodibenz[b,e]o xepin-2-carboxylate, novel nonprostanoid thromboxane A2 (TXA2) receptor antagonists, were synthesized from methyl 11-oxo-6,11-dihydrodibenz[b,e]oxepin-2-carboxylate. The carbonyl group at C11 was converted into a formylmethylene, then into a 1-azadiene moiety by reaction with a 2-aminoformanilide derivative. Stereo- and regioselective elaboration of the unsymmetrical imidazoles was achieved through a sequence of the transformation of E,Z-1-azadiene intermediates to E isomers under acidic conditions followed by cyclization to imidazoles.
Hypoxia-Selective Agents Derived from Quinoxaline 1,4-Di-N-oxides
Monge, Antonio,Palop, Juan A.,Cerain, Adela Lopez de,Senador, Virginia,Martinez-Crespo, Francisko J.,et al.
, p. 1786 - 1792 (2007/10/02)
Hypoxic cells, which are a common feature of solid tumors, but not normal tissues, are resistant to both anticancer drugs and radiation therapy.Thus the identification of drugs with selective toxicity toward hypoxic cells is an important objective in anticancer chemotherapy.The benzotriazine di-N-oxide (SR 4233, Tirapazamine) has been shown to be an efficient and selective cytotoxin for hypoxic cells.Since the bioreductive activation of Tirapazamine is thought to be due to the presence of the 1,4-di-N-oxide moiety, a series of 3-aminoquinoxaline-2-carbonitrile 1,4-di-N-oxides with a range of electron-donating and -withdrawing substituents in the 6- and /or 7- positions has been synthesized and evaluated for toxicity to hypoxic cells.Electrochemical studies of the quinoxaline di-N-oxides and Tirapazamine showed that as the electron-withdrawing nature of the 6(7)-substituent increases, the reduction potential becomes more positive and the compound is more readily reduced.Apart from the unsubstituted 6a and the 6,7-dimethyl derivative 6c, the quinoxaline di-N-oxide have reduction potentials significantly more positive than Tirapazamine (Epc -0.90 V).The most potent cytotoxins to cells in culture were the 6,7-dichloro and 6,7-difluoro derivatives 6i and 6l, which were 30-fold more potent than Tirapazamine.The 6(7)-fluoro and 6(7)-chloro compounds, 6e and 6h, showed the greatest hypoxia selectivity.Four of the compounds, 6e, 6f, 6h and 6i, killed the inner cells of multicellular tumor spheroids in vitro.In vivo Balb/c mice tolerated a dose of these four compounds twice the size of that of Tirapazamine.This study demonstrates that quinoxaline 1,4-di-N-oxides could provide useful hypoxia-selective therapeutic agents.
