The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform

Ranjan Jana - One of the best experts on this subject based on the ideXlab platform.

  • through space 1 4 palladium migration and 1 2 aryl shift direct access to dibenzo a c carbazoles through a triple c h functionalization cascade
    Chemistry: A European Journal, 2015
    Co-Authors: Samir Kumar Bhunia, Arghya Polley, Ramalingam Natarajan, Ranjan Jana
    Abstract:

    A palladium-catalyzed expeditious synthesis of dibenzofused carbazoles from readily available 2-arylindoles and Diaryliodonium Salts is reported. Interestingly, after the electrophilic C3 palladation of indole, an unexpected "through-space" 1,4-palladium migration to the 2-aryl moiety, by remote C-H bond activation followed by C-H arylation with Diaryliodonium Salt, and an unprecedented 1,2-aryl shift take place. Finally, an intramolecular cross-dehydrogenative coupling (CDC) at the C2 position affords dibenzo[a,c]carbazoles in high yields. Remarkably, the present migratory annulation occurs through three C-H bond activation one C-C bond cleavage, and the simultaneous construction of three new C-C bonds in a single operation.

David M Raffel - One of the best experts on this subject based on the ideXlab platform.

  • 18f fluoro hydroxyphenethylguanidines efficient synthesis and comparison of two structural isomers as radiotracers of cardiac sympathetic innervation
    ACS Chemical Neuroscience, 2017
    Co-Authors: Yong Woon Jung, Keun Sam Jang, Robert A Koeppe, Phillip Sherman, Carole A Quesada, David M Raffel
    Abstract:

    Fluorine-18 labeled phenethylguanidines are currently under development in our laboratory as radiotracers for quantifying regional cardiac sympathetic nerve density using PET imaging techniques. In this study, we report an efficient synthesis of 18F-hydroxyphenethylguanidines consisting of nucleophilic aromatic [18F]fluorination of a protected Diaryliodonium Salt precursor followed by a single deprotection step to afford the desired radiolabeled compound. This approach has been shown to reliably produce 4-[18F]fluoro-m-hydroxyphenethylguanidine ([18F]4F-MHPG, [18F]1) and its structural isomer 3-[18F]fluoro-p-hydroxyphenethylguanidine ([18F]3F-PHPG, [18F]2) with good radiochemical yields. Preclinical evaluations of [18F]2 in nonhuman primates were performed to compare its imaging properties, metabolism, and myocardial kinetics with those obtained previously with [18F]1. The results of these studies have demonstrated that [18F]2 exhibits imaging properties comparable to those of [18F]1. Myocardial tracer ki...

  • 4 18f fluoro m hydroxyphenethylguanidine a radiopharmaceutical for quantifying regional cardiac sympathetic nerve density with positron emission tomography
    Journal of Medicinal Chemistry, 2013
    Co-Authors: Keun Sam Jang, Yong Woon Jung, Robert A Koeppe, Phillip Sherman, Carole Quesada, David M Raffel
    Abstract:

    4-[18F]Fluoro-m-hydroxyphenethylguanidine ([18F]4F-MHPG, [18F]1) is a new cardiac sympathetic nerve radiotracer with kinetic properties favorable for quantifying regional nerve density with PET and tracer kinetic analysis. An automated synthesis of [18F]1 was developed in which the intermediate 4-[18F]fluoro-m-tyramine ([18F]16) was prepared using a Diaryliodonium Salt precursor for nucleophilic aromatic [18F]fluorination. In PET imaging studies in rhesus macaque monkeys, [18F]1 demonstrated high quality cardiac images with low uptake in lungs and the liver. Compartmental modeling of [18F]1 kinetics provided net uptake rate constants Ki (mL/min/g wet), and Patlak graphical analysis of [18F]1 kinetics provided Patlak slopes Kp (mL/min/g). In pharmacological blocking studies with the norepinephrine transporter inhibitor desipramine (DMI), each of these quantitative measures declined in a dose-dependent manner with increasing DMI doses. These initial results strongly suggest that [18F]1 can provide quantitat...

  • 4‑[18F]Fluoro‑m‑hydroxyphenethylguanidine: A Radiopharmaceutical for Quantifying Regional Cardiac Sympathetic Nerve Density with Positron Emission Tomography
    2013
    Co-Authors: Keun Sam Jang, Yong Woon Jung, Robert A Koeppe, Phillip S. Sherman, Carole A. Quesada, David M Raffel
    Abstract:

    4-[18F]­Fluoro-m-hydroxyphenethylguanidine ([18F]­4F-MHPG, [18F]1) is a new cardiac sympathetic nerve radiotracer with kinetic properties favorable for quantifying regional nerve density with PET and tracer kinetic analysis. An automated synthesis of [18F]1 was developed in which the intermediate 4-[18F]­fluoro-m-tyramine ([18F]16) was prepared using a Diaryliodonium Salt precursor for nucleophilic aromatic [18F]­fluorination. In PET imaging studies in rhesus macaque monkeys, [18F]1 demonstrated high quality cardiac images with low uptake in lungs and the liver. Compartmental modeling of [18F]1 kinetics provided net uptake rate constants Ki (mL/min/g wet), and Patlak graphical analysis of [18F]1 kinetics provided Patlak slopes Kp (mL/min/g). In pharmacological blocking studies with the norepinephrine transporter inhibitor desipramine (DMI), each of these quantitative measures declined in a dose-dependent manner with increasing DMI doses. These initial results strongly suggest that [18F]1 can provide quantitative measures of regional cardiac sympathetic nerve density in human hearts using PET

Samir Kumar Bhunia - One of the best experts on this subject based on the ideXlab platform.

  • through space 1 4 palladium migration and 1 2 aryl shift direct access to dibenzo a c carbazoles through a triple c h functionalization cascade
    Chemistry: A European Journal, 2015
    Co-Authors: Samir Kumar Bhunia, Arghya Polley, Ramalingam Natarajan, Ranjan Jana
    Abstract:

    A palladium-catalyzed expeditious synthesis of dibenzofused carbazoles from readily available 2-arylindoles and Diaryliodonium Salts is reported. Interestingly, after the electrophilic C3 palladation of indole, an unexpected "through-space" 1,4-palladium migration to the 2-aryl moiety, by remote C-H bond activation followed by C-H arylation with Diaryliodonium Salt, and an unprecedented 1,2-aryl shift take place. Finally, an intramolecular cross-dehydrogenative coupling (CDC) at the C2 position affords dibenzo[a,c]carbazoles in high yields. Remarkably, the present migratory annulation occurs through three C-H bond activation one C-C bond cleavage, and the simultaneous construction of three new C-C bonds in a single operation.

Keun Sam Jang - One of the best experts on this subject based on the ideXlab platform.

  • 18f fluoro hydroxyphenethylguanidines efficient synthesis and comparison of two structural isomers as radiotracers of cardiac sympathetic innervation
    ACS Chemical Neuroscience, 2017
    Co-Authors: Yong Woon Jung, Keun Sam Jang, Robert A Koeppe, Phillip Sherman, Carole A Quesada, David M Raffel
    Abstract:

    Fluorine-18 labeled phenethylguanidines are currently under development in our laboratory as radiotracers for quantifying regional cardiac sympathetic nerve density using PET imaging techniques. In this study, we report an efficient synthesis of 18F-hydroxyphenethylguanidines consisting of nucleophilic aromatic [18F]fluorination of a protected Diaryliodonium Salt precursor followed by a single deprotection step to afford the desired radiolabeled compound. This approach has been shown to reliably produce 4-[18F]fluoro-m-hydroxyphenethylguanidine ([18F]4F-MHPG, [18F]1) and its structural isomer 3-[18F]fluoro-p-hydroxyphenethylguanidine ([18F]3F-PHPG, [18F]2) with good radiochemical yields. Preclinical evaluations of [18F]2 in nonhuman primates were performed to compare its imaging properties, metabolism, and myocardial kinetics with those obtained previously with [18F]1. The results of these studies have demonstrated that [18F]2 exhibits imaging properties comparable to those of [18F]1. Myocardial tracer ki...

  • 4 18f fluoro m hydroxyphenethylguanidine a radiopharmaceutical for quantifying regional cardiac sympathetic nerve density with positron emission tomography
    Journal of Medicinal Chemistry, 2013
    Co-Authors: Keun Sam Jang, Yong Woon Jung, Robert A Koeppe, Phillip Sherman, Carole Quesada, David M Raffel
    Abstract:

    4-[18F]Fluoro-m-hydroxyphenethylguanidine ([18F]4F-MHPG, [18F]1) is a new cardiac sympathetic nerve radiotracer with kinetic properties favorable for quantifying regional nerve density with PET and tracer kinetic analysis. An automated synthesis of [18F]1 was developed in which the intermediate 4-[18F]fluoro-m-tyramine ([18F]16) was prepared using a Diaryliodonium Salt precursor for nucleophilic aromatic [18F]fluorination. In PET imaging studies in rhesus macaque monkeys, [18F]1 demonstrated high quality cardiac images with low uptake in lungs and the liver. Compartmental modeling of [18F]1 kinetics provided net uptake rate constants Ki (mL/min/g wet), and Patlak graphical analysis of [18F]1 kinetics provided Patlak slopes Kp (mL/min/g). In pharmacological blocking studies with the norepinephrine transporter inhibitor desipramine (DMI), each of these quantitative measures declined in a dose-dependent manner with increasing DMI doses. These initial results strongly suggest that [18F]1 can provide quantitat...

  • 4‑[18F]Fluoro‑m‑hydroxyphenethylguanidine: A Radiopharmaceutical for Quantifying Regional Cardiac Sympathetic Nerve Density with Positron Emission Tomography
    2013
    Co-Authors: Keun Sam Jang, Yong Woon Jung, Robert A Koeppe, Phillip S. Sherman, Carole A. Quesada, David M Raffel
    Abstract:

    4-[18F]­Fluoro-m-hydroxyphenethylguanidine ([18F]­4F-MHPG, [18F]1) is a new cardiac sympathetic nerve radiotracer with kinetic properties favorable for quantifying regional nerve density with PET and tracer kinetic analysis. An automated synthesis of [18F]1 was developed in which the intermediate 4-[18F]­fluoro-m-tyramine ([18F]16) was prepared using a Diaryliodonium Salt precursor for nucleophilic aromatic [18F]­fluorination. In PET imaging studies in rhesus macaque monkeys, [18F]1 demonstrated high quality cardiac images with low uptake in lungs and the liver. Compartmental modeling of [18F]1 kinetics provided net uptake rate constants Ki (mL/min/g wet), and Patlak graphical analysis of [18F]1 kinetics provided Patlak slopes Kp (mL/min/g). In pharmacological blocking studies with the norepinephrine transporter inhibitor desipramine (DMI), each of these quantitative measures declined in a dose-dependent manner with increasing DMI doses. These initial results strongly suggest that [18F]1 can provide quantitative measures of regional cardiac sympathetic nerve density in human hearts using PET

  • Approach to the Synthesis of Indoline Derivatives from Diaryliodonium Salts
    2012
    Co-Authors: Kamalkishor P. Landge, Keun Sam Jang, Sang Yeul Lee, Dae Yoon Chi
    Abstract:

    An effective method of constructing the indoline moiety via intramolecular nucleophilic ring closure of a Diaryliodonium Salt is described. Diacetoxyiodoarene compounds (1a–1e) were converted into intermediate Koser’s reagent and coupled with arylstannanes (7–10) to form Diaryliodonium Salts (11a–14e). Indoline compounds with different N-protecting groups, 15, 16, 17, and 18, were synthesized in higher yields by treating Salts (11a–14e) with Cs2CO3 and TEMPO. Regardless of the electronic environment of five para-substituted iodoarenes and the natures of four N-protected arylstannane groups, the conversion proceeded well to afford corresponding indolines in yields of 72–84 and 70–84%, respectively

Claudia Ines Vallo - One of the best experts on this subject based on the ideXlab platform.

  • visible light polymerization of epoxy monomers using an iodonium Salt with camphorquinone ethyl 4 dimethyl aminobenzoate
    Polymer International, 2013
    Co-Authors: Walter F Schroeder, Marco Sangermano, Silvana Valeria Asmussen, Claudia Ines Vallo
    Abstract:

    A visible light initiator system for the photoinduced cationic polymerization of epoxy monomers is reported. The system consists of camphorquinone (CQ) in combination with ethyl-4-dimethyl aminobenzoate (EDMAB) and a Diaryliodonium Salt (Ph2ISbF6.) The three-component system efficiently photoinitiates the polymerization of monomers containing an epoxycyclohexane group, 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexane carboxylate (UVR) and 1,3-bis(3,4-epoxycyclohexyl-2-ethyl),1,1,3,3-tetramethyldisiloxane (SIB), under irradiation with blue light (λ = 467 nm). Very rapid photopolymerization resulted from irradiation of SIB containing Ph2ISbF6 in combination with CQ and better results were obtained in the presence of EDMAB. On the other hand, no polymerization was detected after irradiation of UVR photoactivated with Ph2ISbF6 and CQ. However, this monomer polymerized readily and to high conversion when EDMAB was present. Moreover, almost complete conversion of UVR occurs in the absence of external heating. The polymer resulting from UVR displayed higher values of compressive and flexural properties than the polymer prepared from SIB. This is explained in terms of a higher density of crosslinking points in UVR which is accompanied by a lower content of non-reacted monomer; this has a plasticizing effect on the hardened material. © 2013 Society of Chemical Industry