@ktu.lt
Faculty of Chemical Technology
organic synthesis
Scopus Publications
Emilis Gudelis, Sonata Krikštolaitytė, Monika Stančiauskaitė, Urtė Šachlevičiūtė, Aurimas Bieliauskas, Vaida Milišiūnaitė, Rokas Jankauskas, Neringa Kleizienė, Frank A. Sløk, and Algirdas Šačkus
MDPI AG
In this paper, a simple and efficient synthetic route for the preparation of new heterocyclic amino acid derivatives containing azetidine and oxetane rings was described. The starting (N-Boc-azetidin-3-ylidene)acetate was obtained from (N-Boc)azetidin-3-one by the DBU-catalysed Horner–Wadsworth–Emmons reaction, followed by aza-Michael addition with NH-heterocycles to yield the target functionalised 3-substituted 3-(acetoxymethyl)azetidines. Methyl 2-(oxetan-3-ylidene)acetate was obtained in a similar manner, which was further treated with various (N-Boc-cycloaminyl)amines to yield the target 3-substituted 3-(acetoxymethyl)oxetane compounds. The synthesis and diversification of novel heterocyclic amino acid derivatives were achieved through the Suzuki–Miyaura cross-coupling from the corresponding brominated pyrazole–azetidine hybrid with boronic acids. The structures of the novel heterocyclic compounds were confirmed via 1H-, 13C-, 15N-, and 19F-NMR spectroscopy, as well as HRMS investigations.
Arminas Urbonavičius, Graziana Fortunato, Emilija Ambrazaitytė, Elena Plytninkienė, Aurimas Bieliauskas, Vaida Milišiūnaitė, Renzo Luisi, Eglė Arbačiauskienė, Sonata Krikštolaitytė, and Algirdas Šačkus
MDPI AG
An efficient synthetic route to construct diverse pyrazole-based chalcones from 1-phenyl-1H-pyrazol-3-ols bearing a formyl or acetyl group on the C4 position of pyrazole ring, employing a base-catalysed Claisen–Schmidt condensation reaction, is described. Isomeric chalcones were further reacted with N-hydroxy-4-toluenesulfonamide and regioselective formation of 3,5-disubstituted 1,2-oxazoles was established. The novel pyrazole-chalcones and 1,2-oxazoles were characterized by an in-depth analysis of NMR spectral data, which were obtained through a combination of standard and advanced NMR spectroscopy techniques.
Jolita Bruzgulienė, Greta Račkauskienė, Aurimas Bieliauskas, Vaida Milišiūnaitė, Miglė Dagilienė, Gita Matulevičiūtė, Vytas Martynaitis, Sonata Krikštolaitytė, Frank A Sløk, and Algirdas Šačkus
Beilstein Institut
A convenient and efficient synthesis of novel achiral and chiral heterocyclic amino acid-like building blocks was developed. Regioisomeric methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates were prepared by the reaction of β-enamino ketoesters (including azetidine, pyrrolidine or piperidine enamines) with hydroxylamine hydrochloride. Unambiguous structural assignments were based on chiral HPLC analysis, 1H, 13C, and 15N NMR spectroscopy, HRMS, and single-crystal X-ray diffraction data.
Vaida Milišiūnaitė, Elena Plytninkienė, Roberta Bakšienė, Aurimas Bieliauskas, Sonata Krikštolaitytė, Greta Račkauskienė, Eglė Arbačiauskienė, and Algirdas Šačkus
MDPI AG
A simple and efficient synthetic route to the novel 3a,4-dihydro-3H,7H- and 4H,7H-pyrazolo[4′,3′:5,6]pyrano[4,3-c][1,2]oxazole ring systems from 3-(prop-2-en-1-yloxy)- or 3-(prop-2-yn-1-yloxy)-1H-pyrazole-4-carbaldehyde oximes has been developed by employing the intramolecular nitrile oxide cycloaddition (INOC) reaction as the key step. The configuration of intermediate aldoximes was unambiguously determined using NOESY experimental data and comparison of the magnitudes of 1JCH coupling constants of the iminyl moiety, which were greater by approximately 13 Hz for the predominant syn isomer. The structures of the obtained heterocyclic products were confirmed by detailed 1H, 13C and 15N NMR spectroscopic experiments and HRMS measurements.
Gita Matulevičiūtė, Eglė Arbačiauskienė, Neringa Kleizienė, Vilija Kederienė, Greta Ragaitė, Miglė Dagilienė, Aurimas Bieliauskas, Vaida Milišiūnaitė, Frank A. Sløk, and Algirdas Šačkus
MDPI AG
Series of methyl 3- and 5-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates were developed and regioselectively synthesized as novel heterocyclic amino acids in their N-Boc protected ester form for achiral and chiral building blocks. In the first stage of the synthesis, piperidine-4-carboxylic and (R)- and (S)-piperidine-3-carboxylic acids were converted to the corresponding β-keto esters, which were then treated with N,N-dimethylformamide dimethyl acetal. The subsequent reaction of β-enamine diketones with various N-mono-substituted hydrazines afforded the target 5-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates as major products, and tautomeric NH-pyrazoles prepared from hydrazine hydrate were further N-alkylated with alkyl halides to give 3-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates. The structures of the novel heterocyclic compounds were confirmed by 1H-, 13C-, and 15N-NMR spectroscopy and HRMS investigation.
Vaida Milišiūnaitė, Alena Kadlecová, Asta Žukauskaitė, Karel Doležal, Miroslav Strnad, Jiří Voller, Eglė Arbačiauskienė, Wolfgang Holzer, and Algirdas Šačkus
Springer Science and Business Media LLC
Vaida Milišiūnaitė, Rūta Paulavičiūtė, Eglė Arbačiauskienė, Vytas Martynaitis, Wolfgang Holzer, and Algirdas Šačkus
Beilstein Institut
Fused pyrazole ring systems are common structural motifs of numerous pharmaceutically important compounds. Nevertheless, access to derivatives of the aromatic 2H-furo[2,3-c]pyrazole ring system is still quite limited, and their chemistry and functional properties remain largely underexplored. The current study investigates routes to construct this system from easily accessible starting materials using metal-catalyzed reactions. A simple and efficient procedure to access the 2H-furo[2,3-c]pyrazole ring system was developed by employing the silver(I) ion-mediated ring-closure reaction of 4-alkynyl-3-hydroxy-1-phenyl-1H-pyrazoles as a key step. The required intermediate hydroxyalkynyl substrates for this reaction were prepared by a Pd-catalyzed coupling of 4-iodo-1-phenyl-1H-pyrazol-3-ol with ethyne derivatives. The structures of the obtained target compounds were unequivocally confirmed by detailed 1H, 13C and 15N NMR spectroscopic experiments, HRMS and a single-crystal X-ray diffraction analyses. This silver(I)-mediated 5-endo-dig cyclization of readily available 4-alkynyl-3-hydroxy-1H-pyrazoles can be used as an efficient method to access many novel 2,5-disubstituted 2H-furo[2,3-c]pyrazoles.
Vaida Milišiūnaitė, Eglė Arbačiauskienė, Eva Řezníčková, Radek Jorda, Veronika Malínková, Asta Žukauskaitė, Wolfgang Holzer, Algirdas Šačkus, and Vladimír Kryštof
Elsevier BV
Vaida Milišiūnaitė, Eglė Arbačiauskienė, Aurimas Bieliauskas, Gytė Vilkauskaitė, Algirdas Šačkus, and Wolfgang Holzer
Elsevier BV