The Darzens condensation. Part I. Effect of substituents on the acid-catalysed Darzens condensation

Sipos, Gy.; Schőbel, Gy.; Baláspiri, L.

doi:10.1039/j39700001154

Cited by 5 publications

(3 citation statements)

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“…In the control experiments in methanol, the diastereoselectivity was poor (Table 3, entries 16−19). In terms of reaction rate, yield, and diastereoselectivity, the Cs 2 CO 3promoted reaction (Table 3, entry 19) was the best among the four carbonate-promoted reactions mediated by methanol. This is because Cs 2 CO 3 is the strongest base among the four carbonates and the chelations between M + and the haloenolates are not important in methanol.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Procedure A: 731 mg, 98% yield; white solid; mp 164–165 °C; 1 H NMR (600 MHz, DMSO- d 6 ) δ 8.24 (d, J = 7.7 Hz, 2H), 7.90 (d, J = 7.5 Hz, 2H), 7.66–7.59 (m, 4H), 4.41 (d, J = 2.4 Hz, 1H), 4.23 (d, J = 2.4 Hz, 1H); 13 C NMR (151 MHz, CDCl 3 ) δ 191.3, 148.4, 142.5, 133.9, 132.4, 129.9, 126.7, 124.1, 60.9, 58.0. Product 3g is a known compound …”

Section: Methodsmentioning

confidence: 99%

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Darzens Reaction Rate Enhancement Using Aqueous Media Leading to a High Level of Kinetically Controlled Diastereoselective Synthesis of Steroidal Epoxyketones

2014

J. Org. Chem.

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Darzens reactions between halocarbonyls and aldehydes have been carried out in water in the presence of a Li(+)-containing base, a phase-transfer catalyst, and granular polytetrafluoroethylene under mechanical stirring. Reactions using both aromatic and aliphatic aldehydes produced epoxides stereoselectively in good to excellent yields. This is the first time that aliphatic aldehydes with α-H have been used in aqueous Darzens reactions. The Darzens reactions were much faster in water than in organic solvents. This aqueous rate enhancement occurred for Darzens reactions between enantiopure steroidal haloketones and aldehydes, yielding enantiopure spiroepoxides with a high level of kinetically controlled diastereoselectivity. Chromatography was avoided in the purifications of the steroidal spiroepoxides. This is an example of preparing enantiopure epoxyketones via aqueous Darzens reaction using chiral α-haloketone substrates.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Darzens Reaction Rate Enhancement Using Aqueous Media Leading to a High Level of Kinetically Controlled Diastereoselective Synthesis of Steroidal Epoxyketones

2014

J. Org. Chem.

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“…This method also was applied to the quantitation of esters of trans fatty acids in partially hydrogenated vegetable or marine oils (2,5,6). A large amount of data is available on the FID response correction factors of different lipid classes when analyzed by untreated Chromarods (7)(8)(9). However, relatively little is available on the FID response correction factors for unsaturated geometrical fatty acid isomers and triglycerides when analyzed on AgNO3-Chromarods (2,6).…”

Section: Introductionmentioning

confidence: 99%

Quantitative analyses of methyl esters of fatty acid geometrical isomers, and of triglycerides differing in unsaturation, by the Iatroscan TLC/FID technique using AgNO₃ impregnated rods

Sébédio

Farquharson

Ackman

1985

Lipids

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The relative FID responses for latroscan analyses of cis and trans isomers of methyl esters of 18:1A6, 18:1A9 and 18:1All on Chromarods-S impregnated with AgNO 3 were studied at load levels ranging from 0.5 to 20 ~g, using methyl stearate as internal standard. The FID response correction factors were greater for the cis than for the trans isomers. The correction factors were relatively constant in the 10-20 tzg interval, but increased in the range 0.5-5 tzg.Separation of tristearin, triolein, trilinotein and trilinolenin also was obtained on Chromarods-S impregnated with AgNO 3 using a mixture of benzene:chloroform:acetic acid (90:8:2) as the solvent system. The relative FID responses for the triolein, trilinolein and trilinolenin were determined at load levels ranging from 0.5 to 14.3/~g using tristearin as an internal standard. The FID response correction factors of these three triglycerides differed significantly for load levels of 1.0, 2.5 and 5.0 #g. However, the factors could be considered as being equal in the range 10 to 14,3 tzg.Correction factors were not affected by repeated re-use of the same set of Chromarods. Several hundred separations and scans appeared feasible. Lipids 20: 555-560, 1985.

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Darzens Condensation

2010

Comprehensive Organic Name Reactions and Reagents

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The synthesis of glycidic esters from the condensation between aldehydes or ketones and esters of α‐halo‐carboxylic acids is known as Darzens condensation. This type of condensation has also been extended to α‐halogenated nitriles, sulfoxides, sulfones, sulfoximines, carboxylic amides, etc. The reaction between carbonyl compounds and α‐halogenated ketimine is also referred to as the aza ‐Darzens reaction. This reaction has been modified to occur in the solid‐liquid two‐phase system using a solid base and catalyst at temperatures higher than 100°C.

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The Darzens condensation. Part I. Effect of substituents on the acid-catalysed Darzens condensation

Cited by 5 publications

References 0 publications

Darzens Reaction Rate Enhancement Using Aqueous Media Leading to a High Level of Kinetically Controlled Diastereoselective Synthesis of Steroidal Epoxyketones

Darzens Reaction Rate Enhancement Using Aqueous Media Leading to a High Level of Kinetically Controlled Diastereoselective Synthesis of Steroidal Epoxyketones

Quantitative analyses of methyl esters of fatty acid geometrical isomers, and of triglycerides differing in unsaturation, by the Iatroscan TLC/FID technique using AgNO₃ impregnated rods

Darzens Condensation

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The Darzens condensation. Part I. Effect of substituents on the acid-catalysed Darzens condensation

Cited by 5 publications

References 0 publications

Darzens Reaction Rate Enhancement Using Aqueous Media Leading to a High Level of Kinetically Controlled Diastereoselective Synthesis of Steroidal Epoxyketones

Darzens Reaction Rate Enhancement Using Aqueous Media Leading to a High Level of Kinetically Controlled Diastereoselective Synthesis of Steroidal Epoxyketones

Quantitative analyses of methyl esters of fatty acid geometrical isomers, and of triglycerides differing in unsaturation, by the Iatroscan TLC/FID technique using AgNO3 impregnated rods

Darzens Condensation

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Product

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Quantitative analyses of methyl esters of fatty acid geometrical isomers, and of triglycerides differing in unsaturation, by the Iatroscan TLC/FID technique using AgNO₃ impregnated rods