杂环化学-6

6.2 Quinoline
Nucleophilic substitution reactions
6.2 Quinoline
Nucleophilic substitution reactions
6.2 Quinoline
Side-chain reactivity
6.2 Quinoline
Oxidation
Reactions of pyridine N-oxides
N-Oxidation of pyridine is carried out with peroxy acids and deoxygenation back to pyridine is brought about by a redox reaction with phosphorus(III) compounds such as PCl3, PPh3 or P(OC2H5)3
6.2 Quinoline
Reductions
6.2 Quinoline
Reductions
6.2 Synthesis of Quinoline
6.2 Synthesis of Quinoline
6.2 Synthesis of Quinoline
6.2 Synthesis of Quinoline
6.2 Synthesis of noline
6.2 Synthesis of Quinoline
6.2 Synthesis of Quinoline
6.2 Synthesis of Quinoline
6.2 Synthesis of Quinoline
6.2 Synthesis of Quinoline
6.1 Pyridine
Nucleophilic substitution reactions and metalation
As expected, N-, O-, S- and C-nucleophiles attack the ring C-atoms of pyridine. Addition of the nucleophile and elimination of a pyridine substituent as leaving group occur in a two-step process.
6.2 Quinoline
Electrophilic substitution reactions
Nitration
6.2 Quinoline
Electrophilic substitution reactions
6.2 Quinoline
Electrophilic substitution reactions
6.1 Pyridine
Nucleophilic substitution reactions and metalation
6.1 Pyridine
Nucleophilic substitution reactions and metalation
6.1 Pyridine
Nucleophilic substitution reactions and metalation
6.1 Pyridine
Side-chain reactivity of pyridine
Alkylpyridines undergo reactions analogous to benzene such as side-chain halogenation and oxidative functionalization.
6.1 Synthesis of Pyridine Hetero-Diels-Alder reaction
6.1 Synthesis of Pyridine Pyridine synthesis via ring transformations
6.2 Quinoline
Quinoline is derived from naphthalene by replacement of one of its a-CH groups by nitrogen. 2-and 3-Methylquinoline (quinaldine and lepidine), 2quinolone (carbostyril), 4-quinolone and the quinolinium ion are important derivatives of quinoline.
Pyridine shows complex behaviour towards GRIGNARD reagents.
6.1 Pyridine
Additions of nucleophiles to pyridinium ions
N-Alkylpyridinium ions add hydroxide ions reversibly and exclusively in the 2position, forming 2-hydroxy-l,2-dihydro-N-alkylpyridines which can be oxidized by mild oxidizing agents to N-alkyl-2-pyridones
6.1 Pyridine -----Halogenation Electrophilic substitution reactions
Halogenation of pyridine occurs with elemental chlorine or bromine at high temperature. 3-Halo- and 3,5-dihalopyridines are formed at ca. 300°C as a result of an ionic SEAr process. At higher than 300°C, 2-halo- and 2,6-dihalopyridines are produced, probably by a radical mechanism.
6.1 Pyridine
Reactions of pyridine N-oxides
Pyridine- 1 -oxide undergoes electrophilic and nucleophilic substitution reactions at the 2- and 4-positions, as predicted from its resonance description
6.1 Pyridine
Side-chain reactivity of pyridine
6.1 Pyridine
Side-chain reactivity of pyridine
6.1 Pyridine
Side-chain reactivity of pyridine
6.1 Pyridine
Meth-Cohn synthesis
6.2 Synthesis of Quinoline
6.2 Synthesis of Quinoline
6.2 Synthesis of Quinoline
Quinolines are accessible by ring transformation of other heterocyclic systems.
6.1 Pyridine Reduction
6.1 Synthesis of Pyridine Pyridine synthesis by cyclocondensation
6.1 Synthesis of Pyridine Pyridine synthesis by cycloaddition
6.1 Pyridine
Reactions of pyridine N-oxides
6.1 Pyridine
Reactions of pyridine N-oxides
Pyridine-N-oxides undergo alkylation and acylation at oxygen. O-Alkylation occurs most readily with benzyl halides under mild conditions and leads to 1benzyloxypyridinium ions which in a basic medium, e.g. aqueous alkali, undergo disproportionate into arylaldehydes and pyridine
6.2 Synthesis of Quinoline
6.3 Isoquinoline 异喹啉
Isoquinoline is derived from naphthalene by replacement of a ß-CH group by nitrogen. The isoquinolinium ion and 1-isoquinolone [isoquinolin-1(2H)one, isocarbostyril] are important derivatives of isoquinolines.
6.1 Pyridine -----Sulfonation Electrophilic substitution reactions
Sulfonation of pyridine with oleum at 250°C with Hg(II) catalysis yields the pyridine-3-sulfonic acid in 70% yield
6.1 Pyridine Oxidation
The pyridine ring is remarkably stable towards oxidation. Therefore, pyridine serves as a solvent for oxidation reactions in the Collins oxidation with CrO3. Aqueous KMnO4, preferably in a basic medium, oxidizes pyridine to CO2; peroxy acids bring about Noxidation to pyridine-1-oxide.