Synthesis of novel coumarin derivatives by using Pd-catalysed reactions and their structural characterization

U ovom radu opisana je sinteza derivata 7-hidroksikumarina pripravljenih reakcijom bromiranja, nitriranja, te paladijem kataliziranim reakcijama. Bromiranjem 7-hidroksikumarina s N-bromsukcinimidom uz cerijev amonijev nitrat pripravljeni su 8-brom-7-hidroksikumarin (1) i 3,8-dibrom-7-hidroksikumarin (2). Reakcijom nitriranja 7-hidroksikumarina sintetizirani su derivati kumarina supstituirani nitro skupinom u položajima 3 i/ili 6 i 8 kumarinskog prstena (3-5). 7-hidroksi-4-(3-(p-tolil)prop-2-in-1-il)kumarin (6) supstituiran u položaju C-4 pripravljen je Sonogashira-inom reakcijom unakrsnog povezivanja 7-hidroksi-4-klormetilkumarina s 4-metilfenilacetilenom uz Pd-katalizator. Suzuki-jevom reakcijom 7-hidroksi-4-klormetilkumarina s (4-hidroksifenil)bornom kiselinom uz Pd-katalizator sintetiziran je 7-hidroksi-4-(4-hidroksibenzil)kumarin (7). Strukture sintetiziranih spojeva 1-7 potvrđene su 1H NMR spektroskopijom. Derivati kumarina 1-3 spektroskopski su okarakterizirani UV/Vis i fluorimetrijskom spektroskopijom, te su im određeni maksimumi apsorbancije i valne duljine emisije.This work describes the synthesis of 7-hydroxycoumarin derivatives prepared by the bromination, nitration and palladium-catalyzed reactions. 8-bromo-7-hydroxycoumarin (1) and 3,8-dibromo-7-hydroxycoumarin (2) were prepared by the bromination of 7-hydroxycoumarin with N-bromosuccinimide and ceric ammonium nitrate. Coumarin derivates with nitro group substituted at the positions 3 and/ or 6 and 8 of coumarin ring (3-5) were synthesized by the nitration of 7-hydroxycoumarin. 7-hydroxy-4-(3-(p-tolyl)-2-yn-1-yl)-2H-chromen-2-one (6) substituted at C-4 was prepared by Sonogashira cross-coupling reaction of 4-(chloromethyl)-7-hydroxycoumarin and 2-(p-tolyl)ethyn-1-ylium with Pd-catalyst. 7-hydroxy-4-(4-hydroxybenzyl)-2H-chromen-2-one (7) was synthesized by Suzuki reaction of 4-(chloromethyl)-7-hydroxycoumarin and (4-hydroxyphenyl)boronic acid using Pd-catalyst. The structures of the synthesized compounds 1-7 were confirmed by 1H NMR spectroscopy. Coumarin derivates 1-3 were spectroscopically characterized by UV/ Vis and fluorimetric spectroscopy and their maxima of absorbance and emission wavelengths were determined