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Koprivnica, Croatia

Kolarovic D.L.,BELUPO Pharmaceuticals Inc. | Vinkovic V.,Ruder Boskovic Institute | Litvic M.,BELUPO Pharmaceuticals Inc.
Arkivoc | Year: 2016

A mild, highly efficient synthetic method was developed for the dehydrogenation of 3,4-dihydropyrimidin-2(1H)-ones employing in situ formed tert-butyl hypoiodite under basic conditions. The oxidant was prepared by the reaction of molecular iodine and potassium tertbutoxide. The reaction was carried out in dry tetrahydrofuran at room temperature and high purity products were isolated in high yields after simple work-up. The reaction times (3-10 min.) indicated the new method is superior in comparion to other literature oxidants employed under classical conditions or microwave promoted reactions. Two plausible mechanisms of dehydrogenation were proposed and the active species tert-butyl hypoiodite was characterized by UV/Vis spectroscopy method. ©ARKAT-USA, Inc. Source

Litvic M.,BELUPO Pharmaceuticals Inc. | Vecenaj I.,BELUPO Pharmaceuticals Inc. | Ladisic Z.M.,BELUPO Pharmaceuticals Inc. | Lovric M.,BELUPO Pharmaceuticals Inc. | And 2 more authors.
Tetrahedron | Year: 2010

For the first time hexaaquaaluminium(III) tetrafluoroborate has been used as a mild acid catalyst in organic synthesis. A simple method of its preparation based on the reaction of aluminium triisopropoxide and tetrafluoroboric acid in isopropanol afforded catalyst of high purity and activity. The three-component Biginelli condensation of acetoacetate esters, urea and aldehydes catalyzed by 10 mol % of [Al(H2O)6](BF4)3 in refluxing acetonitrile afforded 3,4-dihydropyrimidonones in good to high yields on multigram scales. The tolerance to acid sensitive reactants such as thienyl and furyl carbaldehydes, applicability to sterically hindered β-ketoesters and simple recyclability without losing catalytic activity make this catalyst as good replacement to literature methods. The mechanism of the reaction includes formation of the so called 'ureido-crotonate' rather than corresponding acylimino intermediate as found with Brønsted type catalysts. © 2010 Elsevier Ltd. All rights reserved. Source

Litvic M.,BELUPO Pharmaceuticals Inc. | Smic K.,BELUPO Pharmaceuticals Inc. | Vinkovic V.,Ruder Boskovic Institute | Filipan-Litvic M.,BELUPO Pharmaceuticals Inc.
Journal of Photochemistry and Photobiology A: Chemistry | Year: 2013

Photodegradation of rosuvastatin calcium (1) under several radiation wavelengths in solid state and solution in solvents of different polarity has been studied. It was shown that 1 is very sensitive, especially in solution, even to low energy wavelengths and main and almost exclusive degradation pathway includes formation of diastereomeric dihydrophenanthrene derivatives (R,S,R)-2 and (S,S,R)-2. Absolute configurations of isolated diastereomeric photoproducts in forms of respective lactones 3 and 4 have been determined. First partial diastereoselective photocyclization of 1 leading 10.5% d.e. of (R,S,R)-2 over (S,S,R)-2 has been determined in water as a solvent. To prevent photodegradation of 1 in solution use of brown glass is necessary. Solid formulations of 1 are efficiently protected against photodegradation by the presence of combination of dyes such as yellow iron oxide and pink color E122 or β-carotene inside the formulation or tablet coating. © 2012 Elsevier B.V. Source

Litvic M.,BELUPO Pharmaceuticals Inc. | Regovic M.,BELUPO Pharmaceuticals Inc. | Smic K.,BELUPO Pharmaceuticals Inc. | Lovric M.,BELUPO Pharmaceuticals Inc. | And 2 more authors.
Bioorganic and Medicinal Chemistry Letters | Year: 2012

Mo(VI) and Mo(V) salts both react selectively with Hantzsch esters to produce substitute pyridines in good-to-excellent yield (75-99%). The remarkable reactivity and selectivity of MoOCl4 under reflux of acetonitrile and MoCl5 in dichloromethane at room temperature encouraged us to propose that molybdenum-containing enzymes (such as xanthine or aldehyde oxidase) also participate to some degree in the metabolism of 1,4-dihydropyridine drugs in the liver analogous to NADH in the respiratory chain. © 2012 Elsevier Ltd. All rights reserved. Source

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