- Synthesis of AZT analogues: 7-(3-azido-2hydroxypropyl)-, 7-(3-amino-2-hydroxypropyl)-, 7-(3-triazolyl-2-hydroxypropyl)theophyllines
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Nucleophilic displacement of the tosyloxy group in 7-(2-hydroxy-3- p -toluenesulfonyloxypropyl)theophylline (1) with azide anion afforded 7-(3-azido-2-hydroxypropyl)theophylline (2). Reduction of the 3-azido group in 2 with Ph 3 P/Py/NH 4 OH afforded the 3-amino derivative 4, alternatively obtained by regioselective amination of 7-(2,3-epoxypropyl)theophylline (3). Selective acetylation of 4 gave the N-acetyl derivative 5. 1,3-Dipolar cycloaddition of the azide group in 2 with N 1 -propargyl thymine (6) afforded the regioisomeric triazole 7. Copyright Taylor & Francis Group, LLC.
- El Ashry, El Sayed,Abdel-Rahman, Adel,Rashed, Nagwa,Awad, Laila,Rasheed, Hanaa
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- Chemoenzymatic synthesis of enantiomerically enriched diprophylline and xanthinol nicotinate
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A concise chemoenzymatic route toward enantiomerically enriched active pharmaceutical ingredients (API) – diprophylline and xanthinol nicotinate – is reported for the first time. The decisive step is an enantioselective lipase-mediated methanolysis of racemic chlorohydrin-synthon acetate, namely 1-chloro-3-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)propan-2-yl acetate, performed under kinetically-controlled conditions on a preparative 500 mg-scale. The best results in terms of reaction enantioselectivity (E = 14) were obtained for the enantiomers resolution performed with lipase type B from Candida antarctica immobilized on acrylic resin (CAL-B, Novozym 435) suspended in homophasic acetonitrile-methanol mixture. The elaborated biocatalytic system furnished the key chlorohydrin intermediate (in 71% ee and 38% yield), which was then smoothly converted into enantioenriched active agents: (R)-(–)-diprophylline (57% ee) and (S)-(+)-xanthinol nicotinate (65% ee). To support the assignment of absolute configurations of EKR-products as well as to confirm the stereochemical outcome of the remaining reaction steps, docking studies toward the prediction of enantiomers binding selectivity in CAL-B active site as well as the respective chemical correlations with enantiomerically enriched analytical standards obtained from commercially available (R)-(–)-epichlorohydrin, were applied. In addition, single-crystal X-ray diffraction (XRD) analyses were performed for the synthesized optically active APIs furnishing by this manner a first crystal structures of nicotinic acid salt of xanthinol.
- Borowiecki, Pawe?,M?ynek, Mateusz,Dranka, Maciej
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- Substituted epoxyalkyl xanthines
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Compounds of the formula STR1 including the resolved enantiomers and/or diastereomers and mixtures thereof wherein each of one or two R is independently STR2 wherein n is 1-16 and R' is H or alkyl(1-4C); and wherein each remaining R is independently H, alkyl(1-6C), alkenyl(1-6C) or benzyl; an wherein said alkyl or alkenyl may be substituted by a hydroxyl, halo, or dimethylamino group, and/or interrupted by an oxygen atom, are useful in modulating the effects of internal and external stimuli on cells by reversing the effects of these stimuli on the short-term secondary messenger pathways. In particular, the compounds lower elevated levels of unsaturated, non-arachidonate phosphatidic acid (PA) and diacylglycerol (DAG) derived from said PA within seconds of the primary stimulus and their contact with said cells. The modulatory effect depends on the nature of the target cell and the stimulus applied.
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