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Electrochemical synthesis of substituted 1,3-oxazolidines from vicinal amino alcohols
No full textU ovom radu opisan je dizajn i razvoj nove, ekonomične i brze elektrokemijske sinteze supstituiranih 1,3-oksazolidina iz vicinalnih amino-alkohola. Priređeni su derivati oksazolidina fuzionirani na desozamin (6 - 8) ili makrolaktonski prsten (11) azitromicina, koji su već ranije priređeni klasičnim metodama organske sinteze. Spomenuti spojevi pokazali su veliki potencijal za protuupalne primjene, stoga je ova efikasnija „zelena“ metoda odlična alternativa za sintezu ovih obećavajućih spojeva. Također, ova metoda testirana je i na manjim molekulama, pri čemu su uspješno priređeni (4S,5R)-N-benzil-3,4-dimetil-5-fenil-oksazolidin-2-imin 14 i N-benzil-1,3a,4,8b-tetrahidroindeno[1,2-d]oksazol-2-imin 17, kao nove potencijalno biološki aktivne molekule. Polazni materijali (odgovarajući amino-alkoholi) za sintezu makrolidnih oksazolidina (6, 7, 8 i 11) bili su demetilirani derivati azitromicina 1, 2 i 9, dok su za sintezu malih molekula 14 i 17 korišteni efedrin-hidroklorid 12 i
(1S,2R)-1-amino-2-indanol 15. Elektrociklizaciji je prethodila klasična sinteza odgovarajućih intermedijera metodama ranije opisanim u literaturi. Korišteni su benzil-izotiocijanat ili fenil-kloroformat kao reagensi, a reakcije su provođene u acetonitrilu uz trietilamin na sobnoj ili povišenoj temperaturi. Sve elektrociklizacijske reakcije provođene su u nepodijeljenoj ćeliji uređaja IKA ElectraSyn 2.0 uz C(+) – C(-) sustav elektroda i acetonitril kao otapalo te koncentraciju elektrolita (LiBr ili NaI) od 0.1 mM. Reakcije su provođene pri konstantnoj struji 5 – 10 mA s promjenom polariteta svakih 15 min. Za elektrokemijsku sintezu spojeva 6 i 14 isproban je i one-pot pristup polazeći od odgovarajućeg vicinalnog amino-alkohola (1 ili 12). Izvedba ovih one-pot reakcija provođena je na povišenoj temperaturi što je znatno usporilo sam korak ciklizacije. Ova metoda pokazala se boljom ne samo zbog svoje brzine i „zelenijeg“ pristupa, već je rezultirala i boljim iskorištenjima od klasičnih procesa. Strukture svih priređenih spojeva potvrđene su 1D i 2D NMR tehnikama.This paper describes the design and development of a new, economical and rapid electrochemical synthesis of substituted 1,3-oxazolidines from vicinal amino alcohols. Using this method, oxazolidine derivatives fused to desosamine (6 - 8) or macrolactone ring (11) of azithromycin, which had prior been prepared by classical methods, were synthesized. These compounds showed great potential for anti-inflammatory applications; therefore, this more efficient "green" method is an excellent alternative for the synthesis of these promising agents. Moreover, to test this method on smaller molecules,
(4S,5R)-N-benzyl-3,4-dimethyl-5-phenyloxazolidin-2-imine 14 and
N-benzyl-1,3a,4,8b-tetrahydroindeno[1,2-d]oxazol-2-imine 17 were prepared, as new potentially biologically active molecules. Starting materials (corresponding amino alcohols), for the synthesis of macrolide oxazolidines (6, 7, 8 and 11), were demethylated derivatives of azithromycin 1, 2 and 9, whereas for the synthesis of small molecules 14 and 17, ephedrine hydrochloride 12 and (1S,2R)-1-amino-2-indanol 15 were used. Electrocyclization was preceded by the classical synthesis of the corresponding intermediates, using methods previously described in the literature. Benzyl isothiocyanate or phenyl chloroformate were used as reagents, and reactions were carried out in acetonitrile with triethylamine at room or increased temperature. All electrocyclization reactions were carried out in an undivided cell of the IKA ElectraSyn 2.0 device with a C(+) – C(-) electrode system, acetonitrile as solvent and an electrolyte concentration (LiBr or NaI) of 0.1 mM. Reactions were carried out at a constant current of 5-10 mA with a change of polarity every 15 min. For the electrochemical synthesis of compounds 6 and 14, one-pot approach, starting from the corresponding vicinal amino alcohol (1 or 12), was tested as well. These one-pot reactions were carried out at an increased temperature, which significantly slowed down the cyclization step itself. This method proved itself to be better than classical synthesis not only because of its speed and "greener" approach, but also due to its greater yields. The structures of all compounds were confirmed by 1D and 2D NMR techniques
Electrochemical synthesis of substituted 1,3-oxazolidines from vicinal amino alcohols
No full textU ovom radu opisan je dizajn i razvoj nove, ekonomične i brze elektrokemijske sinteze supstituiranih 1,3-oksazolidina iz vicinalnih amino-alkohola. Priređeni su derivati oksazolidina fuzionirani na desozamin (6 - 8) ili makrolaktonski prsten (11) azitromicina, koji su već ranije priređeni klasičnim metodama organske sinteze. Spomenuti spojevi pokazali su veliki potencijal za protuupalne primjene, stoga je ova efikasnija „zelena“ metoda odlična alternativa za sintezu ovih obećavajućih spojeva. Također, ova metoda testirana je i na manjim molekulama, pri čemu su uspješno priređeni (4S,5R)-N-benzil-3,4-dimetil-5-fenil-oksazolidin-2-imin 14 i N-benzil-1,3a,4,8b-tetrahidroindeno[1,2-d]oksazol-2-imin 17, kao nove potencijalno biološki aktivne molekule. Polazni materijali (odgovarajući amino-alkoholi) za sintezu makrolidnih oksazolidina (6, 7, 8 i 11) bili su demetilirani derivati azitromicina 1, 2 i 9, dok su za sintezu malih molekula 14 i 17 korišteni efedrin-hidroklorid 12 i
(1S,2R)-1-amino-2-indanol 15. Elektrociklizaciji je prethodila klasična sinteza odgovarajućih intermedijera metodama ranije opisanim u literaturi. Korišteni su benzil-izotiocijanat ili fenil-kloroformat kao reagensi, a reakcije su provođene u acetonitrilu uz trietilamin na sobnoj ili povišenoj temperaturi. Sve elektrociklizacijske reakcije provođene su u nepodijeljenoj ćeliji uređaja IKA ElectraSyn 2.0 uz C(+) – C(-) sustav elektroda i acetonitril kao otapalo te koncentraciju elektrolita (LiBr ili NaI) od 0.1 mM. Reakcije su provođene pri konstantnoj struji 5 – 10 mA s promjenom polariteta svakih 15 min. Za elektrokemijsku sintezu spojeva 6 i 14 isproban je i one-pot pristup polazeći od odgovarajućeg vicinalnog amino-alkohola (1 ili 12). Izvedba ovih one-pot reakcija provođena je na povišenoj temperaturi što je znatno usporilo sam korak ciklizacije. Ova metoda pokazala se boljom ne samo zbog svoje brzine i „zelenijeg“ pristupa, već je rezultirala i boljim iskorištenjima od klasičnih procesa. Strukture svih priređenih spojeva potvrđene su 1D i 2D NMR tehnikama.This paper describes the design and development of a new, economical and rapid electrochemical synthesis of substituted 1,3-oxazolidines from vicinal amino alcohols. Using this method, oxazolidine derivatives fused to desosamine (6 - 8) or macrolactone ring (11) of azithromycin, which had prior been prepared by classical methods, were synthesized. These compounds showed great potential for anti-inflammatory applications; therefore, this more efficient "green" method is an excellent alternative for the synthesis of these promising agents. Moreover, to test this method on smaller molecules,
(4S,5R)-N-benzyl-3,4-dimethyl-5-phenyloxazolidin-2-imine 14 and
N-benzyl-1,3a,4,8b-tetrahydroindeno[1,2-d]oxazol-2-imine 17 were prepared, as new potentially biologically active molecules. Starting materials (corresponding amino alcohols), for the synthesis of macrolide oxazolidines (6, 7, 8 and 11), were demethylated derivatives of azithromycin 1, 2 and 9, whereas for the synthesis of small molecules 14 and 17, ephedrine hydrochloride 12 and (1S,2R)-1-amino-2-indanol 15 were used. Electrocyclization was preceded by the classical synthesis of the corresponding intermediates, using methods previously described in the literature. Benzyl isothiocyanate or phenyl chloroformate were used as reagents, and reactions were carried out in acetonitrile with triethylamine at room or increased temperature. All electrocyclization reactions were carried out in an undivided cell of the IKA ElectraSyn 2.0 device with a C(+) – C(-) electrode system, acetonitrile as solvent and an electrolyte concentration (LiBr or NaI) of 0.1 mM. Reactions were carried out at a constant current of 5-10 mA with a change of polarity every 15 min. For the electrochemical synthesis of compounds 6 and 14, one-pot approach, starting from the corresponding vicinal amino alcohol (1 or 12), was tested as well. These one-pot reactions were carried out at an increased temperature, which significantly slowed down the cyclization step itself. This method proved itself to be better than classical synthesis not only because of its speed and "greener" approach, but also due to its greater yields. The structures of all compounds were confirmed by 1D and 2D NMR techniques
Synthesis of 2,6-disubstituted benzothiazole derivatives using mechanochemistry
No full textU ovom radu opisana je sinteza novih 2-aril-6-cijanobenzotiazolnih derivata kao potencijalnih biološki aktivnih molekula. Za pripravu ciljanih spojeva 5a‒9a, 5b–9b, 5c–9c korištena je ekološki prihvatljiva mehanokemijska sinteza. Potrebni intermedijeri priređeni su višestupnjevitom sintezom. Sinteza fenolnih derivata benzotiazola (4a‒4c) provedena je reakcijom kondenzacije bis(2-amino-5-cijanofenil)disulfida 3 s odgovarajućim benzaldehidima u ekološki prihvatljivom otapalu glicerolu. Bis(2-amino-5-cijanofenil)disulfid 3 priređen je iz 4-amino-3-tiocijanatobenzonitrila 2 reakcijom reduktivne dimerizacije s natrijevim sulfidom u etanolu i vodi, dok je 4-amino-3-tiocijanatobenzonitril 2 priređen reakcijom supstitucije iz 4-aminobenzonitrila 1 i kalijeva tiocijanata uz brom u ledenoj octenoj kiselini. Ciljani 2,6-disupstituirani derivati benzotiazola (5a‒9a, 5b–9b, 5c–9c) priređeni su O-alkiliranjem fenolnih derivata benzotiazola (4a‒4c) s odgovarajućim alkil-halogenidima. Strukture novosintetiziranih derivata potvrđene su spektroskopijom 1H i 13C NMR.In this work synthesis of novel 2-aryl-6-cyanobenzothiazoles as potential bioactive molecules is described. For the preparation of target compounds 5a‒9a, 5b–9b, 5c–9c environmentally friendly mechanochemical synthesis was used. Required intermediates were prepared by multistep synthetic pathway. Phenolic benzothiazole derivatives (4a‒4c) were obtained by condensation of bis(2-amino-5-cyanophenyl)disulphide 3 with corresponding benzaldehydes in green solvent glycerol. Bis(2-amino-5-cyanophenyl)disulphide 3 was prepared by base-promoted reductive dimerization of 4-amino-3-thiocyanatobenzonitrile 2 with sodium sulphide in ethanol / water, while 4-amino-3-thiocyanatobenzonitrile 2 was prepared from 4-aminobenzonitrile 1 and potassium thiocyanate with bromine in acetic acid via substitution reaction. Targeted 2,6-disubstituted benzothiazole derivatives (5a‒9a, 5b–9b, 5c–9c) were prepared through O-alkylation of phenolic benzothiazole derivatives (4a‒4c) with corresponding alkyl-halogenides. The structures of all newly synthesized compounds were confirmed by 1H NMR and 13C NMR spectroscopy
Synthesis of 2,6-disubstituted benzothiazole derivatives using mechanochemistry
No full textU ovom radu opisana je sinteza novih 2-aril-6-cijanobenzotiazolnih derivata kao potencijalnih biološki aktivnih molekula. Za pripravu ciljanih spojeva 5a‒9a, 5b–9b, 5c–9c korištena je ekološki prihvatljiva mehanokemijska sinteza. Potrebni intermedijeri priređeni su višestupnjevitom sintezom. Sinteza fenolnih derivata benzotiazola (4a‒4c) provedena je reakcijom kondenzacije bis(2-amino-5-cijanofenil)disulfida 3 s odgovarajućim benzaldehidima u ekološki prihvatljivom otapalu glicerolu. Bis(2-amino-5-cijanofenil)disulfid 3 priređen je iz 4-amino-3-tiocijanatobenzonitrila 2 reakcijom reduktivne dimerizacije s natrijevim sulfidom u etanolu i vodi, dok je 4-amino-3-tiocijanatobenzonitril 2 priređen reakcijom supstitucije iz 4-aminobenzonitrila 1 i kalijeva tiocijanata uz brom u ledenoj octenoj kiselini. Ciljani 2,6-disupstituirani derivati benzotiazola (5a‒9a, 5b–9b, 5c–9c) priređeni su O-alkiliranjem fenolnih derivata benzotiazola (4a‒4c) s odgovarajućim alkil-halogenidima. Strukture novosintetiziranih derivata potvrđene su spektroskopijom 1H i 13C NMR.In this work synthesis of novel 2-aryl-6-cyanobenzothiazoles as potential bioactive molecules is described. For the preparation of target compounds 5a‒9a, 5b–9b, 5c–9c environmentally friendly mechanochemical synthesis was used. Required intermediates were prepared by multistep synthetic pathway. Phenolic benzothiazole derivatives (4a‒4c) were obtained by condensation of bis(2-amino-5-cyanophenyl)disulphide 3 with corresponding benzaldehydes in green solvent glycerol. Bis(2-amino-5-cyanophenyl)disulphide 3 was prepared by base-promoted reductive dimerization of 4-amino-3-thiocyanatobenzonitrile 2 with sodium sulphide in ethanol / water, while 4-amino-3-thiocyanatobenzonitrile 2 was prepared from 4-aminobenzonitrile 1 and potassium thiocyanate with bromine in acetic acid via substitution reaction. Targeted 2,6-disubstituted benzothiazole derivatives (5a‒9a, 5b–9b, 5c–9c) were prepared through O-alkylation of phenolic benzothiazole derivatives (4a‒4c) with corresponding alkyl-halogenides. The structures of all newly synthesized compounds were confirmed by 1H NMR and 13C NMR spectroscopy
Electrochemical synthesis of substituted 1,3-oxazolidines from vicinal amino alcohols
No full textU ovom radu opisan je dizajn i razvoj nove, ekonomične i brze elektrokemijske sinteze supstituiranih 1,3-oksazolidina iz vicinalnih amino-alkohola. Priređeni su derivati oksazolidina fuzionirani na desozamin (6 - 8) ili makrolaktonski prsten (11) azitromicina, koji su već ranije priređeni klasičnim metodama organske sinteze. Spomenuti spojevi pokazali su veliki potencijal za protuupalne primjene, stoga je ova efikasnija „zelena“ metoda odlična alternativa za sintezu ovih obećavajućih spojeva. Također, ova metoda testirana je i na manjim molekulama, pri čemu su uspješno priređeni (4S,5R)-N-benzil-3,4-dimetil-5-fenil-oksazolidin-2-imin 14 i N-benzil-1,3a,4,8b-tetrahidroindeno[1,2-d]oksazol-2-imin 17, kao nove potencijalno biološki aktivne molekule. Polazni materijali (odgovarajući amino-alkoholi) za sintezu makrolidnih oksazolidina (6, 7, 8 i 11) bili su demetilirani derivati azitromicina 1, 2 i 9, dok su za sintezu malih molekula 14 i 17 korišteni efedrin-hidroklorid 12 i
(1S,2R)-1-amino-2-indanol 15. Elektrociklizaciji je prethodila klasična sinteza odgovarajućih intermedijera metodama ranije opisanim u literaturi. Korišteni su benzil-izotiocijanat ili fenil-kloroformat kao reagensi, a reakcije su provođene u acetonitrilu uz trietilamin na sobnoj ili povišenoj temperaturi. Sve elektrociklizacijske reakcije provođene su u nepodijeljenoj ćeliji uređaja IKA ElectraSyn 2.0 uz C(+) – C(-) sustav elektroda i acetonitril kao otapalo te koncentraciju elektrolita (LiBr ili NaI) od 0.1 mM. Reakcije su provođene pri konstantnoj struji 5 – 10 mA s promjenom polariteta svakih 15 min. Za elektrokemijsku sintezu spojeva 6 i 14 isproban je i one-pot pristup polazeći od odgovarajućeg vicinalnog amino-alkohola (1 ili 12). Izvedba ovih one-pot reakcija provođena je na povišenoj temperaturi što je znatno usporilo sam korak ciklizacije. Ova metoda pokazala se boljom ne samo zbog svoje brzine i „zelenijeg“ pristupa, već je rezultirala i boljim iskorištenjima od klasičnih procesa. Strukture svih priređenih spojeva potvrđene su 1D i 2D NMR tehnikama.This paper describes the design and development of a new, economical and rapid electrochemical synthesis of substituted 1,3-oxazolidines from vicinal amino alcohols. Using this method, oxazolidine derivatives fused to desosamine (6 - 8) or macrolactone ring (11) of azithromycin, which had prior been prepared by classical methods, were synthesized. These compounds showed great potential for anti-inflammatory applications; therefore, this more efficient "green" method is an excellent alternative for the synthesis of these promising agents. Moreover, to test this method on smaller molecules,
(4S,5R)-N-benzyl-3,4-dimethyl-5-phenyloxazolidin-2-imine 14 and
N-benzyl-1,3a,4,8b-tetrahydroindeno[1,2-d]oxazol-2-imine 17 were prepared, as new potentially biologically active molecules. Starting materials (corresponding amino alcohols), for the synthesis of macrolide oxazolidines (6, 7, 8 and 11), were demethylated derivatives of azithromycin 1, 2 and 9, whereas for the synthesis of small molecules 14 and 17, ephedrine hydrochloride 12 and (1S,2R)-1-amino-2-indanol 15 were used. Electrocyclization was preceded by the classical synthesis of the corresponding intermediates, using methods previously described in the literature. Benzyl isothiocyanate or phenyl chloroformate were used as reagents, and reactions were carried out in acetonitrile with triethylamine at room or increased temperature. All electrocyclization reactions were carried out in an undivided cell of the IKA ElectraSyn 2.0 device with a C(+) – C(-) electrode system, acetonitrile as solvent and an electrolyte concentration (LiBr or NaI) of 0.1 mM. Reactions were carried out at a constant current of 5-10 mA with a change of polarity every 15 min. For the electrochemical synthesis of compounds 6 and 14, one-pot approach, starting from the corresponding vicinal amino alcohol (1 or 12), was tested as well. These one-pot reactions were carried out at an increased temperature, which significantly slowed down the cyclization step itself. This method proved itself to be better than classical synthesis not only because of its speed and "greener" approach, but also due to its greater yields. The structures of all compounds were confirmed by 1D and 2D NMR techniques
Synthesis of 2,6-disubstituted benzothiazole derivatives using mechanochemistry
No full textU ovom radu opisana je sinteza novih 2-aril-6-cijanobenzotiazolnih derivata kao potencijalnih biološki aktivnih molekula. Za pripravu ciljanih spojeva 5a‒9a, 5b–9b, 5c–9c korištena je ekološki prihvatljiva mehanokemijska sinteza. Potrebni intermedijeri priređeni su višestupnjevitom sintezom. Sinteza fenolnih derivata benzotiazola (4a‒4c) provedena je reakcijom kondenzacije bis(2-amino-5-cijanofenil)disulfida 3 s odgovarajućim benzaldehidima u ekološki prihvatljivom otapalu glicerolu. Bis(2-amino-5-cijanofenil)disulfid 3 priređen je iz 4-amino-3-tiocijanatobenzonitrila 2 reakcijom reduktivne dimerizacije s natrijevim sulfidom u etanolu i vodi, dok je 4-amino-3-tiocijanatobenzonitril 2 priređen reakcijom supstitucije iz 4-aminobenzonitrila 1 i kalijeva tiocijanata uz brom u ledenoj octenoj kiselini. Ciljani 2,6-disupstituirani derivati benzotiazola (5a‒9a, 5b–9b, 5c–9c) priređeni su O-alkiliranjem fenolnih derivata benzotiazola (4a‒4c) s odgovarajućim alkil-halogenidima. Strukture novosintetiziranih derivata potvrđene su spektroskopijom 1H i 13C NMR.In this work synthesis of novel 2-aryl-6-cyanobenzothiazoles as potential bioactive molecules is described. For the preparation of target compounds 5a‒9a, 5b–9b, 5c–9c environmentally friendly mechanochemical synthesis was used. Required intermediates were prepared by multistep synthetic pathway. Phenolic benzothiazole derivatives (4a‒4c) were obtained by condensation of bis(2-amino-5-cyanophenyl)disulphide 3 with corresponding benzaldehydes in green solvent glycerol. Bis(2-amino-5-cyanophenyl)disulphide 3 was prepared by base-promoted reductive dimerization of 4-amino-3-thiocyanatobenzonitrile 2 with sodium sulphide in ethanol / water, while 4-amino-3-thiocyanatobenzonitrile 2 was prepared from 4-aminobenzonitrile 1 and potassium thiocyanate with bromine in acetic acid via substitution reaction. Targeted 2,6-disubstituted benzothiazole derivatives (5a‒9a, 5b–9b, 5c–9c) were prepared through O-alkylation of phenolic benzothiazole derivatives (4a‒4c) with corresponding alkyl-halogenides. The structures of all newly synthesized compounds were confirmed by 1H NMR and 13C NMR spectroscopy
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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