Synthesis of Nitroxide-Annulated Carbocycles and Heterocycles

New, pyrroline nitroxide annulated lactones, polycycles, and maleimide were synthesized by classical and microwave-assisted methodology. We report the application of the metathesis reaction in the presence of nitroxide yielding a pyrroline nitroxide condensed 1,4-benzoquinone as a paramagnetic dienophile. The formation of the isoselenazolone-fused pyrroline ring system was examined and different reactivity was observed with pyrrolin-1-oxyl and pyrroline derivatives

Facile syntheses of 3,4-disubstituted pyrroline nitroxides and their further synthetic applications

Lithiation of an alfa,beta-unsaturated pyrroline nitroxide ester with LTMP at the beta-carbon followed by treatment with electrophiles led to a new series of 3,4-disubstituted pyrroline nitroxides, which could be used as valuable paramagnetic building blocks. The new compounds were tested in Sonogashira and Stille cross coupling reactions, which offered methyl 1-oxyl-4-substituted-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-carboxylate radicals for new C-C bond formation in poor to moderate yields. The reaction of an alfa,beta-unsaturated pyrroline nitroxide ester with methyl chloroformate generated diester 2b; the partial hydrolysis product of this reaction was shown to be a key compound for the synthesis of paramagnetic uracil derivative 10

Synthesis of Deprenyl-like nitroxide free radicals and their diamagnetic derivatives

Synthesis of paramagnetically modified deprenyl and oxotremorine is reported. Starting from 5- and 6-membered 2,5-disubstituted nitrones (1, 6) or 4-phenyl-2,5,5-trimethyl-1H-pyrroline 1-oxide (11) deprenyl or oxotremorine like nitroxides were synthesized via Grignard reactions. The corresponding pre-nitroxides with propargylamine structure were achieved by reduction of nitroxides followed by methylation

Synthesis of nem paramagnetic retinal analogues

New paramagnetic retinal analogues have been synthesized by Horner-Wadsworth-Emmons and Wittig reactions. In these new analogues the pyrroline nitroxide moiety is situated in the place of Beta-ionone ring or at the end of the polyene chain

Új, diamágneses és paramágneses fluoreszcens molekulák szintézise és alkalmazása = Synthesis and application of new diamagnetic and paramagnetic fluorophores

Új, kettősen (spin és fluoreszcens) jelölő reagenseket szintetizáltunk danzil-, BODIPY- kumarin-, pirén és benzodiazafurazán típusú fluorofórokkal. A danzil fluorofórt sikeresen alkalmazták a növényfiziológiai kutatásokban a stresszfolyamatokban képződő reaktív oxigén származékok (ROS) kimutatására, míg a lipofil oldallánccal ellátott kettősen jelölő vegyülettel a laktoglobulin kötőhelyeit tanulmányoztuk külföldi partnerekkel együttmüködésben. SH-csoport jelölésére alkalmas fluoreszcens reagenst és fluoroionofor vegyületeket szintetizáltunk. Módszert dolgoztunk ki paramágneses vinil-jodidok és paramágneses boronsavak szintézisére. Ezek Pd-katalizált keresztkapcsolási reakciókban hasznosíthatók ill. szóba jöhet a paramágneses boronsav szénhidrát spin-próbakénti alkalmazása. Szénciklusokhoz és heterociklusokhoz kapcsolt ill. azokkal kondenzált nitroxidokat állítottunk elő. Az új vegyületek között paramágneses bioaktív, komplexképző és spinjelző vegyületet találunk. A paramágnesesen módosított biomolekulák képesek a danzilszármazékokhoz hasonlóan képesek a ROS-okat csapdázni, így a gyógyszer gyökfogó sajátsággal rendelkezik. | New double (spin and fluorescence) sensor reagents were synthesized with dansyl-, couma-rin-, BODIPY-, pyrene- and benzodiazafurazan fluorophores with different emission/excitation wavelengths. The dansyl-type double sensors were used to detect reactive oxygen species (ROS) formed under stress conditions in plants. A double label reagent was used in mapping of hydrophobic binding sites of lactoglobulin. We have synthesized new SH-specific fluorescence labels and fluoroionophores. Paramagnetic vinyl iodides and boronic acids were synthesized, which can be used in Pd-catalyzed cross-coupling processes. The paramagnetic boronic acids may be considered as useful spin probes for carbohydrates labeling. Various, new paramagnetically modified carbo- and heterocycles were synthesized including modifications of ligands, drugs with nitroxides. New crosslinking spin labels were also synthesized. The drug molecules, modified with nitroxides or their precursors are also capable of trapping free radicals similarly to dansylated nitroxide precursor sensor reagents

Synthesis and potential use of 1,8-naphthalimide type O-1(2) sensor molecules

New double (fluorescent and spin) sensor molecules containing 4-amino substituted 1,8-naphthalimide as a fluorophore and a sterically hindered amine (pre-nitroxide) or pyrroline nitroxide as a quencher and radical capturing moiety were synthesized. All sensors were substituted with a diethylaminoethyl side-chain to increase the water solubility. Steady state fluorescence properties of these compounds and their responses to ROS in vitro are reported with perspectives of plant physiology use in vivo

Synthesis of Azoles Condensed with, or Linked to, Nitroxides

Nitroxides connected to indoles, tetrazoles, or 1,3,4-oxadiazoles were synthesized by conventional and microwave-assisted cyclization reactions. New approaches to pyrrole-, pyrazole-, and triazoleannulated nitroxides are described. We showed that Diels–Alder reactions of the N-tert-butoxycarbonyl derivative of (4,4,6,6-tetramethyl- 2,4,6,7-tetrahydro-5H-pyrrolo[3,4-c]pyridin-5-yl)oxidanyl gave polycyclic scaffolds condensed with a six-membered nitroxide

Kinetics of rapid covalent bond formation of aniline with humic acid: ESR investigations with nitroxide spin labels

ABSTRACT The bioavailability of many soil contaminants depends on their interaction with the soil organic matter. The paper presents a new approach of using stable paramagnetic spin labels for investigating the kinetics of covalent binding of specific xenobiotic functional groups with humic acids, a major organic matter fraction. Leonardite humic acid (LHA) was incubated with the nitroxide spin labels amino-TEMPO (4-amino-2,2,6,6-Tetramethylpiperidin-1-oxyl) and anilino-NO (2,5,5-Trimethyl-2-(3-aminophenyl)pyrrolidin-1-oxyl), respectively, which contain an aliphatic or aromatic functionality susceptible to interaction with LHA. Electron spin resonance (ESR) spectra of LHA samples without and with the enzyme laccase were recorded at X-band frequency (9.43 GHz) at room temperature and neutral pH. Binding was detected by a pronounced broadening of the spectral lines after incubation of LHA for both spin labels. The development of a broad signal component in the spectrum of anilino-NO indicated the immobilization due to strong binding of the aniline group. The reorientational correlation time of bound anilino-NO is more than two orders of magnitude greater than that of the free label. The ratio of the amount of bound to the unbound species was used to determine the kinetics of the covalent bond formation. Reaction rate constants of 0.16 min-1 and 0.01 min-1 were determined corresponding to half-times of 4.3 min and 69.3 min, respectively. Treatment of LHA with laccase enhanced the amount of the reacting anilino-NO species by a factor of 7.6, but left the reaction rate unaltered. Oxidative radical coupling was excluded by using the spin trap agent n-tert-butyl-alpha-phenylnitrone

Synthesis of new spin labels for Cu-free click conjugation

New pyrroline nitroxides attached to a terminal acetylenic sulfone, a dibenzocyclooctyne or a cyclooctyne carboxylic acid were synthesized and tested in Cu-free click reactions to conjugate these new spin labels with 4-azido-TEMPO, azidophenylalanine and an azidophenylalanine-containing protein