Highly Stereoselective Synthesis of β-Amino Ketones via a Mannich Reaction Catalyzed by Cellulose Sulfuric Acid as a Biodegradable,Efficient, and Recyclable Heterogeneous Catalyst

The efficient use of cellulose sulfuric acid as a heterogeneous catalyst promotes three-component, one-pot Mannich reaction of various ketones, aromatic aldehydes, and aromatic amines in ethanol to make the corresponding β-amino ketones with high stereoselectivity in favor of the anti-isomer. This protocol has several advantages such as good yield, mild reaction conditions, no environmental hazards, and simple workup procedure.      

Regioselective Intramolecular Carbon-Hydrogen Insertion in Copper-Catalyzed Carbenoid Decompositions of cis-1-Methyl-3-Arylcyclohexane-1-Diazomethyl Ketones : Some Synthetic Applications

Recently, we have developed¹ a new route for the stereo-specific introduction of an angular carboxyl or functionalized methyl groups² in a rigid hydrophenanthrene moiety. The key step in this approach is a regioselective intramolecular α-keto carbenoid insertion across the benzylic C-H bond (at C-4a) in CuSO₄-catalyzed thermal decomposition of the diazoketones and to the corresponding tetracyclic ketones and in moderate to good yields. A modified procedure³ of carbenoid decomposition of these diazoketones, in the presence of Cu₂O under irradiation with tungsten filament lamp, improves the yields of the desired C-H insertion products. Thus, the ketones and have been prepared now in consistently higher yields (53-55%) from the pure diazoketones , m.p. 125-127°, and , m.p.     

Hydrosilylation of Ketones Catalyzed with Mg-Al-O-t-Bu Hydrotalcite

In this article, a simple and efficient procedure of hydrosilylation of ketones catalyzed with Mg-Al-O-t-Bu hydrotalcite was described. Hydrosilylation of ketones with triethoxysilane was carried out smoothly at room temperature in the presence of Mg-Al-O-t-Bu hydrotalcite without solvent, and the conversions of ketones were more than 90%. The recyclability of Mg-Al-O-t-Bu hydrotalcite was also tested.      

PPh3-KOBut–Mediated Cyclization Reaction of β-Ketoesters with Alkynyl Ketones: Synthesis of Functionalized 2-Pyrones

Cyclization of alkynyl ketones with β-ketoesters mediated by PPh₃ and KOBu^t to synthesize 2-pyrone derivatives was systematically described. A variety of β-ketoesters reacted with alkynyl ketones to give functionalized 2-pyrones in moderate to good yields under mild conditions.      

Biginelli-Like Cyclocondensation Reaction: Efficient Synthesis of 4,6-Diarylpyrimidin-2(1H)-one Under Solvent-Free Conditions

An efficient and facile synthesis of 4,6-diarylpyrimidin-2(1H)-one via a Biginelli-like reaction of aromatic aldehydes, aromatic ketones, and urea in the presence of NaOH under solvent-free conditions using a heating method has been developed. Compared with the classical reaction conditions, this new synthetic method has the advantages of excellent yields, shorter reaction time, and mild reaction conditions.      

Direct α-alkylation of ketones with primary alcohols catalyzed by iridium–CNP complex

The α-alkylation of ketones with primary alcohols was realized by CC cross-coupling with iridium–CNP complexes as catalyst. This reaction proceeds via dehydrogenation reactions, aldol condensation, and hydrogenation using the borrowed hydrogen atoms from alcohols. The pyridyl methanols and other heterocyclic substituted methanols, especially alkyl alcohols, were also suitable for this transformation.     

Novel and Selective Method for the Aerobic Oxidation of Benzylic Alcohols in the Absence of Metal Catalyst

A metal-free aerobic oxidation of benzylic alcohols to the corresponding benzylaldehyde derivatives was accomplished using proton ionic liquids (pyridium nitrate) as catalyst in a nonsolvent system with excellent conversion and selectivity. The catalyst could be recycled with no other polluted emission in this reaction procedure.      

The Reaction of (Phenyldimethylsilyl)dichloromethyllithium with Organoboranes. A Synthesis of α-Hydroxyorganosilanes and Ketones

The α-transfer reaction of organoboranes has been utilized to great advantage in the employment of organoboranes in synthesis.² We report here that this process can be used as illustrated in eq 1 to generate α-hydroxyorganosilanes, which can be converted to ketones. This procedure serves to incorporate two of the groups of the organoborane into the product as well as generating the hydroxyl group via oxidation of the newly formed carbon-boron bond.     

Acid catalyzed aldol condensations of ketones with glyoxylic acid: A simple single-step synthesis of 4-oxo-2,5-heptdienedioic acids

Abstract

The acid catalyzed condensations of ketones with glyoxylic acid at 80?°C, under neat conditions gives 4-oxo-2,5-heptdienedioic acids in 56–88% yield. The solid state photochemical dimerization of 4-oxo-2,5-heptdienedioic acid under UV light gives 2,7-dioxo-tricyclo[6.2.0.0^3,6]decane-4,5,9,10-tetracarboxylic acid in 90% yield.

     

Synthesis of Bis(indolyl) Methanes in Catalyst- and Solvent-Free Reaction

Efficient synthesis of bis(indolyl) methanes by the reaction of indoles with various carbonyl compounds in the absence of catalyst and solvent afforded the corresponding bis(indolyl) methanes in excellent yields.     

Convenient Method for the Friedel–Crafts Acylation of Benzene Derivatives Using Silver Nitrate as Catalyst

Friedel–Crafts acylation of benzene derivatives such as anisole, toluene, and xylene has been successively carried out using silver nitrate as the catalyst in the presence of an eco friendly solvent (ethyl alcohol). Both benzoyl chloride and acetyl chloride reacted smoothly under the conditions to afford the corresponding ketones in good yield.

Symmetrical Ketones from Aldehyde Trimethylsilyl Enol Ethers on Storage: A Cautionary Note

The widespread use of trialkylsilyl enol ethers has dramatically increased the utility of enolate anion chemistry.¹ These enol ethers are readily prepared, reactive, and in many instances are stable enough to be commercially available. We have been using trimethylsilyl enol ethers as aldehyde enolate precursors and wish to report some observations regarding storage of these 1-alkyl-2-trimethylsilyloxyethenes. We have noted that after 2–3 months in sealed glass ampuoles these trimethylsilyl enol ethers contained significant amounts of symmetrical ketones.     

Deoxygenation of Aromatic Ketones Using Transfer Hydrogenolysis with Raney Nickel in 2-Propanol

Aryl ketones are readily deoxygenated to their corresponding aryl alkanes upon treatment with Raney nickel catalyst in boiling 2-propanol.

Novel Procedure for the Coupling of Sterically Hindered Electron-Deficient Anilines to the 6-Position of the Purine Core

Sterically hindered electron-deficient anilines are coupled to the 6-position of the purine core only when activated as their corresponding TFA-amide. The free anilines did not react under all conditions tested. After aqueous work-up, the TFA-group is lost.

This procedure provides a new tool in the construction of purines functionalized with a sterically hindered electron-deficient aniline in the 6-position.      

Mild and Efficient Deoxygenation of Sulfoxides to Sulfides with Cp2TiCl2/Gallium System

The Cp₂TiCl₂/Ga system was found to be a new reagent for reducing a variety of sulfoxides to the corresponding sulfides in good to excellent yields under mild conditions.      

Reaction of Methylenecyclobutanes with NXS-H2O System

Reactions of methylenecyclobutanes (MCBs) with NXS-H₂O system were investigated. The results were quite different from that of methylenecyclopropanes (MCPs), and an interesting aryl-transfer reaction happened to give substituted cyclobutyl ketones as products when disubstituted MCBs were employed. When monosubstituted MCBs were employed, the direct halohydroxylation gave the cyclobutyl ring untouched adducts. All of these analogs have potential application value in organic synthesis.

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