Β-hydroxyl Ketones Research Articles

Facile access to β-hydroxyl ketones via a cobalt-catalyzed ring-opening/hydroxylation cascade of cyclopropanols

A cobalt-catalyzed ring-opening/hydroxylation cascade of highly strained cyclopropanols has been developed for the first time. The reaction was conducted under open-air atmosphere to afford a broad series of structurally diverse β-hydroxy ketones in moderate to good yields with high regioselectivity. The protocol features mild reaction conditions, simple operation, high-functional-group tolerance, facile scalability, and heterocycle compatibility.

Electromediated Aldol Reaction in EtOH/H2O

An environment-friendly electromediated aldol reaction is reported here. With KI as mediator, ketones and aldehydes could be readily converted into β-hydroxyl ketones in EtOH/H2O. A variety of functionalities were compatible with this safe and green method. Mechanism of this transformation was explored with control experiments and cyclic voltammetry.

Precision Research on Ginger: The Type of Ginger Matters.

Ginger is a widely consumed spice and possesses numerous pharmacological properties. However, studies addressing the efficacy of ginger in humans have been inconsistent. Many confounding factors need to be considered when evaluating the health effects from ginger against chronic diseases, especially the levels of bioactive components in the ginger formulations used in human trials. Gingerols, the major compounds in fresh ginger, are liable to dehydrate and convert to shogaols, the major compounds in dried ginger, as a result of the instability of β-hydroxyl ketone when exposed to heat and/or acidic conditions. As a result of various heating and processing methods, the concentrations of gingerols and shogaols in ginger products vary significantly. Increasing evidence has shown that gingerols and shogaols have different bioactivities, molecular targets, and metabolic pathways, suggesting the importance of identifying the optimal oral ginger composition for a specific disease. In this perspective, we highlighted differences in the composition between fresh ginger and dry ginger, bioactivities, molecular targets, and metabolic pathways of gingerols and shogaols as well as future perspectives regarding precision research on ginger.

Bismuth trichloride-catalyzed oxy-Michael addition of water and alcohol to α,β-unsaturated ketones

An efficient method was developed for the conjugate addition of water to various α,β-unsaturated ketones by using bismuth(III) chloride as a catalyst. The reactions proceeded smoothly in the presence of a catalytic amount of BiCl3 (20 mol%) in aqueous media to furnish a variety of synthetically useful β-hydroxyl ketones in moderate to good yields. Apart from water molecule, various alcohols could also be employed as nucleophiles to react with α,β-unsaturated ketones, leading to β-alkoxyl ketones in modest to high yields. In addition, the mild reaction conditions also entailed the conjugate addition reactions to proceed with the tolerance to a range of functional groups.

Chromium(III)-Catalyzed Addition of Water and Alcohol to α,β-Unsaturated Ketones for the Synthesis of β-Hydroxyl and β-Alkoxyl Ketones in Aqueous Media.

An efficient chromium(III) chloride-catalyzed Michael-type reaction of water or alcohol with α,β-unsaturated ketones is developed. A variety of α,β-unsaturated ketones effectively reacted with either water or alcohols to give the corresponding β-hydroxyl ketones or β-alkoxyl ketones in modest to high yields with excellent compatibility to various functional groups. The approach was further utilized for the preparation of synthetically useful compounds containing tetrahydrofuran skeleton.

NH2OH–Mediated Lignin Conversion to Isoxazole and Nitrile

Conversion of lignin to aromatic compounds via C–C/C–O bond cleavage has been an attractive but challenging subject in recent years. We herein report the first protocol that converts lignin models and preoxidized lignin to isoxazole and aromatic nitrile. The isoxazole motif is constructed by condensation of β-hydroxyl ketone with hydroxylamine. Magnesium oxide promotes an oximation reaction and an intramolecular condensation. Aromatic nitriles and esters are obtained via Beckmann rearrangement or an acidolysis reaction depending on the selected additive. The hydroxylamine-mediated strategy works well for the preoxidized lignin conversion to aromatic isoxazole, nitrile, and ester monomers with up to 7.6% yield.

Occurrence, biological activity and metabolism of 6-shogaol.

As one of the main bioactive compounds of dried ginger, 6-shogaol has been widely used to alleviate many ailments. It is also a major pungent flavor component, and its precursor prior to dehydration is 6-gingerol, which is reported to be responsible for the pungent flavor and biological activity of fresh ginger. Structurally, gingerols including 6-gingerol have a β-hydroxyl ketone moiety and is liable to dehydrate to generate an α,β-unsaturated ketone under heat and/or acidic conditions. The conjugation of the α,β-unsaturated ketone skeleton in the chemical structure of 6-shogaol explicates its higher potency and efficacy than 6-gingerol in terms of antioxidant, anti-inflammatory, anticancer, antiemetic and other bioactivities. Research on the health benefits of 6-shogaol has been conducted and results have been reported recently; however, scientific data are scattered due to a lack of systematic collection. In addition, action mechanisms of the preventive and/or therapeutic actions of 6-shogaol remain obscurely non-collective. Herein, we review the preparations, biological activity and mechanisms, and metabolism of 6-shogaol as well as the properties of 6-shogaol metabolites.

Iodine(III)-Mediated Oxy-fluorination of Alkenyl Oximes: An Easy Path to Monofluoromethyl-Substituted Isoxazolines.

A highly regioselective intramolecular oxy-fluorination of alkenyl oximes was achieved. This new transformation represents an efficient method for the preparation of monofluoromethyl-substituted isoxazolines. The synthetic application of the oxy-fluorination product was demonstrated by a one-step synthesis of monofluoromethyl-substituted β-hydroxyl ketone derivatives.

Reformatsky Reaction Promoted by an Ionic Liquid ([Bmim]Cl) in the Synthesis of β-Hydroxyl Ketone Derivatives Bearing a Coumarin Unit

A number of β-hydroxy-ketone derivatives bearing a coumarin unit have been synthesised by the Reformatsky reaction of formyl coumarin and α-bromoacetophenone in an ionic liquid (1-butyl-3-methylimidazolium chloride, [Bmim]Cl). The recovered ionic liquid can be reused at least five times without a significant reduction in yield. This procedure is green, mild and environmentally benign.

Efficient one-pot selective reduction of esters in β-ketoesters using LiHMDS and lithium aluminium hydride

The ester functionality in β-keto esters is selectively reduced in one-pot, first by enolization using LiHMDS and then reduced with lithium aluminium hydride. This method produces β-hydroxyl ketones from the corresponding β-keto esters in high yield.

L‐Prolinamide Catalyzed Aqueous Direct Aldol Reaction: An Environment‐Friendly Method for the Synthesis of β‐Hydroxylketones.

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Direct aldol reactions catalyzed by 1,1,3,3-tetramethylguanidine lactate without solvent

The ionic liquid, 1,1,3,3-tetramethylguanidine lactate ([TMG][Lac]), was used as a recyclable catalyst for direct aldol reactions at room temperature without any solvent. The results demonstrated that good chemo- and regio-selectivity could be achieved, and the ionic liquid can be easily recovered and recycled without considerable decrease of activity. The protocol is green and effective for producing β-hydroxyl ketones.

An efficient and practical synthesis of β-hydroxyl ketones catalysed by trisodium phosphate under ultrasound

In the presence of trisodium phosphate, cross-aldol reactions of reactive aldehydes with substituted acetophenone in CH3OH-water mixed solvent afford β-hydroxyl ketones in good to excellent yields under ultrasound irradiation.

Environmentally Friendly and Efficient Process for the Preparation of β‐Hydroxyl Ketones.

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Environmentally Friendly and Efficient Process for the Preparation of β-Hydroxyl Ketones

An environmentally benign and efficient process for the preparation of β-hydroxyl ketones was developed by the practical cross-aldol reactions of 2-acetylpyridine, acetophenone, and cyclohexanone with 4-nitro-, 3-nitro-, and 2-nitrobenzaldehydes in water catalyzed by Na2CO3 in very high yields.