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Pyridine

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Pyridine - Free Register to Access Experts & Abstracts

Sunil N. Chavan - One of the best experts on this subject based on the ideXlab platform.

Jose L Garciaruano - One of the best experts on this subject based on the ideXlab platform.

  • mild regioselective halogenation of activated Pyridines with n bromosuccinimide
    Synthesis, 2001
    Co-Authors: Victoria Canibano, Mercedes Santos, Ascension M Sanztejedor, Carmen M Carreno, Jonathan Rodriguez, Gema Gonzalez, Jose L Garciaruano
    Abstract:

    Regioselective mono and dihalogenations of amino, hydroxy and methoxy Pyridines (2-, 3-, and 4-substituted) as well as 2,6-dimethoxy Pyridine with N-bromosuccinimide in different solvents have been studied. Reactivity of the substrates decreases in the order amino>hydroxy>methoxy and regioselectivity depends on the position of the substituent (2-substituted > 3-substituted). In most of the cases we obtained monobrominated derivatives regioselectively and in high yields. Hydroxy and amino Pyridines can also be dibrominated in almost quantitative yield with 2 equivalents of NBS.

Christopher F Pigge - One of the best experts on this subject based on the ideXlab platform.

  • alkylidene dihydroPyridines as synthetic intermediates model studies toward the synthesis of the bis piperidine alkaloid xestoproxamine c
    Journal of Organic Chemistry, 2016
    Co-Authors: Ashabha I Lansakara, S Santhana V Mariappan, Christopher F Pigge
    Abstract:

    Results of model studies demonstrating a stereoselective synthetic route to tricyclic analogues of the bis(piperidine) alkaloid xestoproxamine C are presented. Dearomatization of a tricyclic Pyridine derivative to afford an alkylidene dihydroPyridine (anhydrobase) intermediate followed by catalytic heterogeneous hydrogenation was used to install the correct relative stereochemistry about the bis(piperidine) ring system. Other key features of these model studies include development of an efficient ring-closing metathesis procedure to prepare macrocyclic derivatives of 3,4-disusbstituted Pyridines, intramolecular cyclizations of alkylidene dihydroPyridines to establish Pyridine-substituted pyrrolidines and piperidines, successful homologation of Pyridine-4-carboxaldehydes using formaldehyde dimethyl thioacetal monoxide (FAMSO), and application of B-alkyl Suzuki coupling to assemble substituted Pyridines.

Neil K. Garg - One of the best experts on this subject based on the ideXlab platform.

  • Regioselective reactions of 3,4-pyridynes enabled by the aryne distortion model
    Nature Chemistry, 2013
    Co-Authors: Adam E. Goetz, Neil K. Garg
    Abstract:

    The Pyridine heterocycle continues to play a vital role in the development of human medicines. More than 100 currently marketed drugs contain this privileged unit, which remains highly sought after synthetically. We report an efficient means to access di- and trisubstituted Pyridines in an efficient and highly controlled manner using transient 3,4-pyridyne intermediates. Previous efforts to employ 3,4-pyridynes for the construction of substituted Pyridines were hampered by a lack of regiocontrol or the inability to later manipulate an adjacent directing group. The strategy relies on the use of proximal halide or sulfamate substituents to perturb pyridyne distortion, which in turn governs regioselectivities in nucleophilic addition and cycloaddition reactions. After trapping of the pyridynes generated in situ , the neighbouring directing groups may be removed or exploited using versatile metal-catalysed cross-coupling reactions. This methodology now renders 3,4-pyridynes as useful synthetic building blocks for the creation of highly decorated derivatives of the medicinally privileged Pyridine heterocycle. The in situ trapping of pyridynes is an efficient method for the generation of a variety of substituted Pyridines but, until now, the method has been hampered by a lack of regiocontrol. Here, proximal halide and sulfamate substituents are shown to perturb pyridyne distortion and thus govern regioselectivities in pyridyne reactions.

Raghunath B. Toche - One of the best experts on this subject based on the ideXlab platform.