Some Observations on the Pechmann Reaction<sup>1</sup>

Winkler, D. E.; Whetstone, R. R.

doi:10.1021/jo01062a034

Cited by 8 publications

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“…Solvent evaporation and purification by flash column chromatography on silica gel (40% ethyl acetate in hexane) gave 6 (2.64 g, 88% yield) as a white solid, m p 127–128 °C (lit. 49 128–128.5°C). IR (neat) 1697 (s, >C=O) cm −1 ; 1 H NMR (500 MHz, CD 3 OD) δ 6.21 (d, J = 2.0 Hz, 2H, ArH), 6.18 (t, J = 2.0 Hz, 1H, ArH), 3.4 (s, 2H, benzylic); mass spectrum (ESI) m/z (relative intensity) 169 (M + +H, 100), 123 (42).…”

Section: Methodsmentioning

confidence: 99%

“…The residue was dissolved in ethyl acetate and washed with water and brine and dried (MgSO 4 ). Solvent evaporation and purification by flash column chromatography on silica gel (40% ethyl acetate in hexane) gave 6 (2.64 g, 88% yield) as a white solid, mp 127–128 °C (lit . 128–128.5 °C).…”

Section: Methodsmentioning

confidence: 99%

“…2-(3,5-Dihydroxyphenyl)acetic Acid (6). 49 To a stirred solution of 5 (3.5 g, 17.8 mmol) in dry CH 2 Cl 2 (85 mL) at −78 °C, under an argon atmosphere, was added boron tribromide (62.3 mL, 62.3 mmol, 1 M solution in CH 2 Cl 2 ). Following this addition, the reaction temperature was gradually raised over a period of 3 h to 25 °C, and the stirring was continued at that temperature until the reaction was completed (4 h).…”

Section: Journal Of Medicinal Chemistrymentioning

confidence: 99%

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Controlled-Deactivation Cannabinergic Ligands

et al. 2013

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We report an approach for obtaining novel cannabinoid analogs with controllable deactivation and improved druggability. Our design involves the incorporation of a metabolically labile ester group at the 2'-position on a series of (−)-Δ8-THC analogs. We have sought to introduce benzylic substituents alpha to the ester group which affect the half-lives of deactivation through enzymatic activity while enhancing the affinities and efficacies of individual ligands for the CB1 and CB2 receptors. The 1'-(S)-methyl, 1'-gem-dimethyl and 1'-cyclobutyl analogs exhibit remarkably high affinities for both CB receptors. The novel ligands are susceptible to enzymatic hydrolysis by plasma esterases in a controllable manner while their metabolites are inactive at the CB receptors. In further in vitro and in vivo experiments key analogs were shown to be potent CB1 receptor agonists and exhibit CB1-mediated hypothermic and analgesic effects.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Journal Of Medicinal Chemistrymentioning

confidence: 99%

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Controlled-Deactivation Cannabinergic Ligands

et al. 2013

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“…As an important moiety of coumarin derivatives, 3:4‐fused six‐member carbocyclic ring coumarins (3:4‐carbocyclic fused ring system) are receiving growing interests due to their biological activities . Typically, there are five kinds of 3:4‐fused six‐member carbocyclic ring coumarins (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…). Among them, derivatives of 7,8,9,10‐tetrahydro‐6 H ‐benzo[ c ]chromen‐6‐ones (a) and 6 H ‐dibenzo[ c ]pyran‐ 6‐ones (e) are well developed and documented, while other kinds of them, such as derivatives of 9,10‐dihydro‐6 H ‐benzo[ c ]chromen‐6‐ones (b) , 7,10‐dihydro‐6 H ‐benzo[ c ]chromen‐6‐ones (c) , especially 7,8‐dihydro‐6 H ‐benzo[ c ]chromen‐ 6‐ones (d), are relatively seldom discussed in the literature, to the best of our knowledge.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Self‐Assembled Helical Supramolecular Polymer of Ethyl 7,8‐dihydro‐3‐hydroxy‐9‐methyl‐7‐(4′‐nitrophenyl)‐6H‐dibenzo[c]‐ pyran‐6‐one‐8‐carboxylate

Chen

Zhang

et al. 2013

Heteroatom Chemistry

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A structurally novel compound was isolated as the main product of tandem Pechmann–dehydration between diethyl 4‐hydroxy‐4‐methyl‐2‐(4′‐nitrophenyl)‐6‐oxocyclohexane‐1,3‐dicarboxylate (1) and resorcinol in the presence of trifluoroacetic acid. The structure of the product was determined as a racemate of (7R,8R)‐ and (7S,8S)‐ethyl 7,8‐dihydro‐3‐hydroxy‐9‐methyl‐7‐(4′‐nitrophenyl)‐6H‐dibenzo[c]‐pyran‐6‐one‐8‐carboxylate (3a) enantiomers by single crystal X‐ray diffraction analysis. The X‐ray crystal structure revealed that 3a possesses an extended and more stable conjugated aromatic system as a consequence of the stereoselectivity of intramolecular dehydration behavior of Pechmann condensation product 2. In the crystal superstructure, the (7R,8R)‐ and (7S,8S)‐isomers of 3a respectively self‐assembled into left‐ and right‐handed supramolecular helical chains with a channel size of 3.70 Å × 10.20 Å in virtue of intermolecular hydrogen bonding together with dramatic twisting between carboxylate group at C8 and tricyclic ring framework of 3a, which are then arranged alternatively along the b‐axis direction with a pitch length of 7.894 Å.

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Pechmann Reaction

2010

Comprehensive Organic Name Reactions and Reagents

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This reaction is an acid‐promoted synthesis of coumarin derivatives from the condensation of phenols and β‐ketoesters or β‐keto carboxylic acids and is generally known as the Pechmann reaction. This reaction, under acidic conditions, involves an esterification or transesterification, followed by a cyclization and dehydration. It has been found that the outcome of this reaction depends on the nature of phenols, β‐keto esters, and condensation reagents. The study finds that only phenols with electron‐donating groups at the meta ‐position of the hydroxy group readily undergo the Pechman condensation. On the other hand, the α‐substituents and γ‐substituents on β‐keto esters retard this reaction. This reaction has general application in the preparation of coumarin derivatives.

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Some Observations on the Pechmann Reaction¹

Cited by 8 publications

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Controlled-Deactivation Cannabinergic Ligands

Controlled-Deactivation Cannabinergic Ligands

Synthesis and Self‐Assembled Helical Supramolecular Polymer of Ethyl 7,8‐dihydro‐3‐hydroxy‐9‐methyl‐7‐(4′‐nitrophenyl)‐6H‐dibenzo[c]‐ pyran‐6‐one‐8‐carboxylate

Pechmann Reaction

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Some Observations on the Pechmann Reaction1

Cited by 8 publications

References 0 publications

Controlled-Deactivation Cannabinergic Ligands

Controlled-Deactivation Cannabinergic Ligands

Synthesis and Self‐Assembled Helical Supramolecular Polymer of Ethyl 7,8‐dihydro‐3‐hydroxy‐9‐methyl‐7‐(4′‐nitrophenyl)‐6H‐dibenzo[c]‐ pyran‐6‐one‐8‐carboxylate

Pechmann Reaction

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Some Observations on the Pechmann Reaction¹