Reactions of enamines. XIII. Tautomerism of enamines

Červinka, O.; Hub, L.

doi:10.1135/cccc19653111

Cited by 11 publications

(6 citation statements)

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“…The product 2 had [a]2D -24.20°(c 0.83, ethanol). The alcohol 1-(4'methoxyphenyl)ethanol 2 was first resolved by Balfe et al (1946) Cervinka, 1965) by asymmetric reduction of the corresponding ketone, and was assigned the (R) configuration. Okamoto et al (1975) obtained the alcohol 2 by resolution, with [alb8 +15.020 (neat), and calculated its maximum rotation to be +45.2°(neat), by using an n.m.r.…”

Section: Characterization Of the Product From Pseudomonas Putida Cellsmentioning

confidence: 99%

Stereochemistry of 1-(4′-hydroxyphenyl)ethanol produced by hydroxylation of 4-ethylphenol by p-cresol methylhydroxylase

McIntire¹,

Hopper²,

Craig³

et al. 1984

Biochemical Journal

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Enzymic hydroxylation of 4-ethylphenol by (a) Pseudomonas putida and (b) highly purified p-cresol methylhydroxylase gave optically active 1-(4'-hydroxyphenyl)-ethanol. The products were transformed into the phenolic methyl ethers and shown to contain 69.5% and 65.6%, respectively, of the (S)-(-)-isomer. The stereochemistry of the reaction is discussed in terms of three distinct steps occurring at the active site of the enzyme.

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Section: Characterization Of the Product From Pseudomonas Putida Cellsmentioning

confidence: 99%

Stereochemistry of 1-(4′-hydroxyphenyl)ethanol produced by hydroxylation of 4-ethylphenol by p-cresol methylhydroxylase

McIntire¹,

Hopper²,

Craig³

et al. 1984

Biochemical Journal

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“…4-Methylpyridine (12). 4-Methylpyridine (12) on heating in 49% HCOOH at 350 "C for 2 h showed a 59.6% conversion into 1,4-dimethyl-(10, 14.9%), 1formyl-4-methyl-(27, 36.5%) and 1 -(3-methylpentyl)-4-methyl-piperidine (28, 5.1 %) together with smaller amounts of 1-ethyl-4-methyl-(14, 1.4%) and l-butyl-4-methyl-piperidine (18, 1.6%) ( Table 5).…”

Section: -Methylpiperidine (8) Plus 3-methyl-1-pentenementioning

confidence: 99%

Aqueous high-temperature chemistry of carbo- and heterocycles: Part 24. First demonstration of specific C-C bond scission of the pyridine ring. Reactions of piperidine, pyridine and some of their methyl derivatives in aqueous formic acid

et al. 1996

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In its reactions with the title compounds, formic acid variously acts as a formylating, methylating, and reducing agent. Both pyridine and piperidine are converted in significant amounts into 1‐methyl‐, 1‐ethyl‐, 1‐propyl‐ and 1‐pentyl‐piperidines. Of the N‐alkyl groups, isotopic labeling shows that only N‐methyl derives from the formic acid, while the N‐ethyl and N‐propyl arise from heterocyclic ring C‐C bond scission by retro‐vinylogous‐bis‐aza‐Aldol reactions. Detailed analysis of the products for pyridine, piperidine, and their 4‐methyl derivatives, reacted separately and mixed, supports mechanisms in which a piperidine adds 1,2 to a pyridinium cation, or to a di‐ or tetra‐hydropyridine, to initiate reaction sequences leading to the product slates found.

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“…The larger-ring lactams yield mainly acyclic amino ketones as the sole pro duct [69][70][71][72][73][74]. [75] …”

Section: + C 6 H 5 Mgbrmentioning

confidence: 99%

Enamines

1971

Organic Chemistry: A Series of Monographs

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The chemistry of enamines has been described in several reviews [25][26][27][28][29] and in a recent monograph [30]. CONDENSATION REACTIONS A. Condensation of Secondary Amines with Aldehydes and KetonesThe most widely used method for preparing enamines involves the conden sation of aldehydes and ketones with secondary amines (Eq. 6). In 1936, Mannich and Davidsen [31] were the first to describe the reaction of secondary amines with aldehydes in the presence of anhydrous potassium carbonate at approximately 0°C to give enamines (Eqs. 6, 7). R-CH 2 CH=0 + 2HNR , R-C-CH R' + HNRJ II oMannich and Davidsen [31] also reported that most of the aldehydes were first converted to a diamino intermediate which on distillation afforded the enamine. Less successful was the attempt to extend the reaction to ketones. Only with the use of calcium oxide at elevated temperatures were the enamines directly obtained, but in poor yields. Herr and Heyl [32,33] found that better yields of enamines from ketones can be obtained by the azeotropic removal of water in the presence or absence [32,33] of acid catalysts [12a, b, 34, 35]

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Reactions of enamines. XIII. Tautomerism of enamines

Cited by 11 publications

References 0 publications

Stereochemistry of 1-(4′-hydroxyphenyl)ethanol produced by hydroxylation of 4-ethylphenol by p-cresol methylhydroxylase

Stereochemistry of 1-(4′-hydroxyphenyl)ethanol produced by hydroxylation of 4-ethylphenol by p-cresol methylhydroxylase

Aqueous high-temperature chemistry of carbo- and heterocycles: Part 24. First demonstration of specific C-C bond scission of the pyridine ring. Reactions of piperidine, pyridine and some of their methyl derivatives in aqueous formic acid

Enamines

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