- Structurally Simple Benzylidene-Type Photolabile Diol Protecting Groups
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Two structurally simple photolabile protecting groups for releasing 1,2- and 1,3-diols have been developed. The diols can be protected in high yields and released from their corresponding acetals with high chemical efficiency.
- Ding, Xiong,Devalankar, Dattatray A.,Wang, Pengfei
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p. 5396 - 5399
(2016/11/06)
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- The use of electroosmotic flow as a pumping mechanism for semi-preparative scale continuous flow synthesis
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By employing a series of reactions we demonstrate the use of electroosmotic flow as a continuous pumping mechanism suitable for semi-preparative scale synthesis, affording an array of small organic compounds, of analytical purity, with yields ranging from 0.57-1.71 g h-1. The Royal Society of Chemistry.
- Wiles, Charlotte,Watts, Paul,Haswell, Stephen J.
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p. 966 - 968
(2007/12/31)
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- Ion pairing effects on the regioselectivity of arylic versus benzylic C-O bond reductive cleavage: synthetic applications
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The regioselectivity of the reductive cleavage of 3,4,5-trimethoxybenzyl methyl ether strongly depends on the alkali metal employed as a reducing agent and solvent effects. Reactions run using Na as a reducing agent led to aromatic C(4)-O bond cleavage, whilst reductions run in the presence of Na/15-crown-5, or using Li as a reducing agent, led to highly regioselective benzylic C-O bond cleavage. This regioselectivity turnaround is discussed in terms of major solvent effects affecting the fragmentation paths of a common reaction intermediate. Synthetic applications of these findings led to the synthesis of biologically active compounds, like 2,5-dialkyl-substituted resorcinols, or 1-(3,4,5-trimethoxyphenyl)-2-arylethanes structurally related to combretastatin.
- Azzena, Ugo,Dettori, Giovanna,Mascia, Ilaria,Pisano, Luisa,Pittalis, Mario
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p. 11998 - 12006
(2008/03/14)
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- Acid-catalysed synthesis and deprotection of dimethyl acetals in a miniaturised electroosmotic flow reactor
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Through incorporating a series of polymer-supported acid catalysts into a miniaturised EOF-based flow reactor, we demonstrate a clean and efficient technique for the protection of aldehydes as their respective dimethyl acetal. In addition, we also report the acid catalysed deacetalisation of 11 dimethyl acetals to their respective aldehyde. In all cases, the compounds described are obtained in high yield (>95%) and excellent purity (>99%) without the need for further product purification.
- Wiles, Charlotte,Watts, Paul,Haswell, Stephen J.
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p. 5209 - 5217
(2007/10/03)
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- Synthesis and complement inhibitory activity of B/C/D-Ring analogues of the fungal metabolite 6,7-diformyl-3′,4′,4a′,5′,6′,7′,8 ′,8a′-octahydro-4,6′,7′-trihydroxy-2′, 5′,5′,8a′-tetramethylspiro[1′(2′H)- naphthalene-2(3H)-benzofuran]
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This paper reports the synthesis and the bioassay of 4-methoxy- and 4-hydroxyspiro[benzofuran2(3H)-cyclohexane] partial analogues (5) of the complement inhibitory sesquiterpene fungal metabolite 6,7-diformyl-3′,4′,4a′,5′,6′,7′, 8′,8a′-octahydro-4,6′,7′-trihydroxy-2′, 5′,5′,8a′-tetramethylspiro[1′(2′H)- naphthalene-2 (3H)-benzofuran] (1a, K-76) and its silver oxide oxidized product (lb, K-76COOH). The described target compounds represent spirobenzofuran B/C/D-ring analogues lacking the A-ring component of the prototype structure. The target compounds were evaluated by the inhibition of total hemolytic complement activity in human serum. It was observed that the structurally simplified analogue 4-methoxyspiro[benzofuran-2(3H)cyclohexane]-6-carboxylic acid (5a) exhibited an IC50 = 0.53 mM similar to the IC50 = 0.57 mM that was observed for the natural product derivative 1b. Exhibiting an IC50 = 0.16 mM, the three-ringed partial structure 6-carboxy-7-formyl-4-methoxyspiro[benzofuran-2(3H)-cyclohexane] (5k)was found to be the most potent target compound. Like the natural product, 5k appears to inhibit primarily at the C5 activation step and inhibits both the classical and alternative human complement pathways. Several other analogues inhibited complement activation in vitro at concentrations similar to those required for inhibition by the natural product 1b.
- Bradbury, Barton J.,Bartyzel, Piotr,Kaufman, Teodoro S.,Nieto, Marcelo J.,Sindelar, Robert D.,Scesney, Susanne M.,Gaumond, Bruce R.,Marsh Jr., Henry C.
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p. 2697 - 2705
(2007/10/03)
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- Structure-activity relationship for DNA topoisomerase II-induced DNA cleavage by azatoxin analogues
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Eighteen analogues of the nonintercalative DNA topoisomerase II (topo II)-active epipodophyllotoxin-ellipticine hybrid, azatoxin, were synthesized and evaluated for their ability to induce topo II-mediated DNA strand breaks in vitro. In general, the SAR p
- Madalengoitia, Jose S.,Tepe, Jetze J.,Werbovetz, Karl A.,Lehnert, Erich K.,Macdonald, Timothy L.
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p. 1807 - 1815
(2007/10/03)
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- Regioselective Reductive Electrophilic Substitution of Derivatives of 3,4,5-Trimethoxybenzaldehyde
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The behavior of several protected derivatives of 3,4,5-trimethoxybenzaldehyde has been investigated under conditions of electron transfer from alkali metals in aprotic solvents.The 4-methoxy group can be regioselectively removed in good to high yield under such conditions, and an appropriate choice of the protecting group, metal, and solvent allows its substitution with a variety of electrophiles. 3,4,5-Trimethoxybenzaldehyde dimethyl acetal, 1, is the starting material of choice for a new general synthetic approach to several polysubstituted resorcinol dimethyl ethers.Investigation of the mechanism of demethoxymetylation, with the aid of labeling experiments, showed that reductive demethoxylation is strongly influenced by the nature of the aldehyde protective group employed.
- Azzena, Ugo,Melloni, Giovanni,Piroddi, Anna Maria,Azara, Emanuela,Contini, Stefania,Fenude, Emma
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p. 3101 - 3106
(2007/10/02)
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- FORMATION OF 2,2-Spiro-SUBSTITUTED 2,3-DIHYDROBENZOFURANS.
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Routes from substituted resorcinols to spiro-substituted dihydrobenzofurans are described.Whilst use of acid-catalysed condensations between a resorcinol and an aldehyde only gave low yields of dihydrobenzofurans and lacked regiocontrol, use of a nucleophilic aromatic substitution approach was successful.
- Morrison, George A.,Sammes, Peter G.,Simmonds, James P.
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p. 1037 - 1050
(2007/10/02)
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