Synthetic applications of N-N linked heterocycles. Part 7. The preparation of 4-alkyl- and 4-aryl-pyridines by regiospecific attack of Grignard reagents ? to quaternary nitrogen in N-(2,6-dimethyl-4-oxopyridin-1-yl)pyridinium salts

Katritzky, Alan R.; Beltrami, Hector; Sammes, M. P.

doi:10.1039/p19800002480

Cited by 26 publications

(12 citation statements)

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“…For all of the products, the analytical data for each molecule was in accordance to that previously reported [18] and additional references can be found accordingly as indicated: 2-methylpyridine [20]; 2,5-dimethylpyridine [21]; 2,4-dimethylpyridine [22]; 2-methyl-4- tert -butylpyridine [23]; 2-methyl-3-phenylpyridine [24]; 2-methyl-4-phenylpyridine [25]; 2-methyl-4-(dimethylamino)pyridine [26].…”

Section: Methodssupporting

confidence: 77%

Flow Synthesis of 2-Methylpyridines via α-Methylation

Manansala

Tranmer

2015

Molecules

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A series of simple 2-methylpyridines were synthesized in an expedited and convenient manner using a simplified bench-top continuous flow setup. The reactions proceeded with a high degree of selectivity, producing α-methylated pyridines in a much greener fashion than is possible using conventional batch reaction protocols. Eight 2-methylated pyridines were produced by progressing starting material through a column packed with Raney ® nickel using a low boiling point alcohol (1-propanol) at high temperature. Simple collection and removal of the solvent gave products in very good yields that were suitable for further use without additional work-up or purification. Overall, this continuous flow method represents a synthetically useful protocol that is superior to batch processes in terms of shorter reaction times, increased safety, avoidance of work-up procedures, and reduced waste. A brief discussion of the possible mechanism(s) of the reaction is also presented which involves heterogeneous catalysis and/or a Ladenberg rearrangement, with the proposed methyl source as C1 of the primary alcohol.

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Section: Methodssupporting

confidence: 77%

Flow Synthesis of 2-Methylpyridines via α-Methylation

Manansala

Tranmer

2015

Molecules

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“…After concentration, the oil, which was chromatographed on silica gel (AcOEt/EP 30:70), gave 84b, 84c, and 84f (yields: 80, 50, and 60 %), the properties of which are similar to those of the known products. [63][64][65] The same process applied to 85b gave 86b, which for R 3 = OMe is similar to a compound (60 % yield) described in the literature. [66] Similarly, 87c gave 84c (50 %), 88 (30 %), and a trace of lactone 63c.…”

Section: Aerial Oxidation Of Dihydropyridinesmentioning

confidence: 71%

Bis(trimethylsilyl)ketene Acetals as C,O‐Dinucleophiles: One‐Pot Formation of Polycyclic γ‐ and δ‐Lactones from Pyridines and Pyrazines

Rudler

Denise

et al. 2005

Eur J Org Chem

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Bis(trimethylsilyl)ketene acetals react with pyridines, quinoline and isoquinoline in the presence of stoichiometric amounts of methyl chloroformate to give the corresponding dihydropyridine-, dihydroquinoline-and dihydroisoquinoline-substituted carboxylic acids in satisfactory yields. The regio-and diastereoselectivities of the addition reactions, together with the presence or absence of rotamers, have been established. The isolated acids react with peracids to give β-hydroxy-δ-lactones through an intramolecular reaction. Similar lactonizations could also be brought about directly from the azaaromatic compounds in one-pot reactions with silica

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“…The generation of the alkoxide is critical for the C6-alkylation with high regioselectivity. The products can be good precursors for asymmetric hydrogenation reactions. , Although it is beyond the scope of this review, N -activated azines − and two-step nucleophilic addition/oxidations − are widely utilized for the synthesis of substituted pyridines.…”

Section: Snar Reactions Of Azines −mentioning

confidence: 99%

C–H Functionalization of Azines

et al. 2017

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Azines, which are six-membered aromatic compounds containing one or more nitrogen atoms, serve as ubiquitous structural cores of aromatic species with important applications in biological and materials sciences. Among a variety of synthetic approaches toward azines, C-H functionalization represents the most rapid and atom-economical transformation, and it is advantageous for the late-stage functionalization of azine-containing functional molecules. Since azines have several C-H bonds with different reactivities, the development of new reactions that allow for the functionalization of azines in a regioselective fashion has comprised a central issue. This review describes recent advances in the C-H functionalization of azines categorized as follows: (1) SAr reactions, (2) radical reactions, (3) deprotonation/functionalization, and (4) metal-catalyzed reactions.

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Synthetic applications of N-N linked heterocycles. Part 7. The preparation of 4-alkyl- and 4-aryl-pyridines by regiospecific attack of Grignard reagents ? to quaternary nitrogen in N-(2,6-dimethyl-4-oxopyridin-1-yl)pyridinium salts

Cited by 26 publications

References 0 publications

Flow Synthesis of 2-Methylpyridines via α-Methylation

Flow Synthesis of 2-Methylpyridines via α-Methylation

Bis(trimethylsilyl)ketene Acetals as C,O‐Dinucleophiles: One‐Pot Formation of Polycyclic γ‐ and δ‐Lactones from Pyridines and Pyrazines

C–H Functionalization of Azines

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