Direct Esterification of Carboxylic Acids with Alcohols Catalyzed by Iron(III) Acetylacetonate Complex

Direct condensation of carboxylic acids and alcohols with electronic, steric, and functional group variations was carried out using the environmentally benign, moisture-stable, inexpensive, and recoverable iron(III) acetylacetonate [Fe(acac)₃] as catalyst (5 mol%). This iron salt efficiently catalyzed the esterification of several primary and secondary alcohols in refluxing xylene, without the need for a dehydration reagent. The chemoselectivity of the proposed protocol was demonstrated by the selective esterification of primary alcohol functionality in racemic 1-phenylethane-1,2-diol with benzoic acid. The esterification was also applicable to unmasked α -hydroxyacid, guasiaromatic, heterocyclic, and N-protected amino acids.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Improved Enantioselective Synthesis of Protected (3S,4S)-4-Amino-3,5-dihydroxypentanoic Acid (ADPA)

An improved enantioselective synthesis of protected (3S,4S)-4-amino-3,5-dihydroxypentanoic acid (ADPA) from L-serine has been developed. Enantioselectivity is improved by replacing the methyl ester with the tert-butyl ester and using neutral magnesium salt of esters to give β-keto ester.     

Indium(III) Chloride: An Efficient Catalyst for the Synthesis of Amidoalkyl Naphthols

Indium chloride was found to be a very efficient catalyst for the synthesis of amidoalkyl naphthols from β-naphthol, aromatic aldehydes, and acetamide/urea under solvent-free conditions using microwave irradiation.     

Synthesis of Bis(phosphonatomethyl)-, Bis(phosphinatomethyl)-, and Bis(phosphinoxidomethyl)amines,as Well as Related Ring Bis(phosphine) Platinum Complexes

The double Kabachnik–Fields condensation of primary amines with 2 equivalents of the other reagents (formaldehyde and a >P(O)H species, such as dialkyl phosphites, diphenylphosphine oxide, as well as the related dioxaphosphorine and oxaphosphorine derivatives) carried out under microwave conditions afforded the title products in 79–94% yields. The bis(phosphinoxidomethyl)amines were converted, after double deoxygenation, to the corresponding ring platinum complexes.

SOCl2/β-Cyclodextrin: A New and Efficient Catalytic System for Beckmann Rearrangement and Dehydration of Aldoximes Under Aqueous Condition

A rapid and efficient synthesis of amides via Beckmann rearrangement of ketoximes and dehydration of aldoximes to corresponding nitriles with good to excellent yields has been carried out in the presence of SOCl₂/β-cyclodextrin under aqueous conditions. The β-cyclodextrin has been recovered and reused.     

Efficient Synthesis of α,β-Diamino Acid Derivatives by In(III)-Catalyzed Regioselective Addition of Amines to Aziridines

An efficient catalytic method for the synthesis of α, β-diamino acid derivatives has been developed via regioselective ring opening of aziridines by amines in the presence of indium(III) salt under very mild reaction conditions.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Kinetics and Equilibria for Complex Formation between Palladium(II) and Chloroacetate

Kinetics and equilibria for the formation of a 1:1 complex between palladium(II) and chloroacetate were studied by spectrophotometric measurements in 1.00 mol HClO₄ at 298.2 K. The equilibrium constant, K, of the reaction

Highly Efficient One-Pot,Three-Component Synthesis of β-Aminoketones Catalyzed by Fe(O2CCF3)3

A highly efficient one-pot, three-component synthesis of β-aminoketones was demonstrated using the cost-effective, noncorrosive, and easily available Fe(O₂CCF₃)₃ as a catalyst for the first time. The method can be employed to synthesize a wide range of target compounds and to introduce different functional groups into the β-aminoketone skeleton. Additionally, the method consistently has the advantages of good yields, short reaction time, and simply experimental workup procedure, which makes it a useful process for the synthesis of functionalized β-aminoketones.     

One-Pot Approach to the Conversion of Alcohols into α-Iodo-α,β-unsaturated Esters

(Carboethoxymethylene)triphenylphosphorane 1 can undergo the tandem reaction of iodination–oxidation–Wittig reaction with alcohol in the presence of N-iodosuccinimide (NIS) and manganese dioxide. The reaction constitutes a stereoselective one-pot procedure for the preparation of Z-configured α-iodo-α,β-unsaturated esters in good to excellent yield.     

Aqueous-Phase Synthesis of α-Hydroxyphosphonates Catalyzed by β-Cyclodextrin

α-Hydroxyphosphonates were synthesized from aromatic/heteroaromatic aldehydes with triethyl phosphite in the presence of β-cyclodextrin in an aqueous medium. The β-cyclodextrin can be recovered and reused without loss of catalytic activity.     

Aza-Michael Addition of Amines to α,β-Unsaturated Compounds Using Molecular Iodine as Catalyst

Aza-Michael adducts are obtained in very good yields by the conjugate addition of aliphatic amines to α,β-unsaturated compounds using molecular iodine as catalyst in dichloromethane at room temperature. Aromatic amines were found to be reactive under reflux in toluene.     

Mild and Efficient Method for Synthesis of Eaminones Using Ytterbium Triflate as Catalyst

A mild and efficient procedure for synthesis of β-enaminones by the condensation of β-dicarbonyl compounds and amines using ytterbium triflate [Yb(OTf)₃] as catalyst is described. The catalyst can be easily recovered and reused without loss of activity.     

Efficient Aziridination of α,β-Unsaturated Ketones with O-(2,4-Dinitrophenyl)-hydroxylamine

The aziridination of α,β-unsaturated ketones with O-(2,4-dinitrophenyl)-hydroxylamine and tertiary amine was developed. trans-Aziridines were obtained exclusively in good yields. The reaction is proposed to occur via an aminimide intermediate.     

Synthesis of new α-hydroxyphosphonates and α-acetoxyphosphonates

A series of new α-hydroxyphosphonate (5–14) have been synthesized in high yields by reaction of β-chloro-α,β-unsaturated aldehydes (1–4) and trialkyl phosphite in the presence of chlorotrimethylsilane at room temperature under solvent-free conditions. In addition, compounds (5–14) were reacted with acetic anhydride in DBU to give the new α-acetoxyphosphonate derivatives (15–23). All these phosphonates (5–23) were obtained as mixtures of two (E and Z) isomers and fully characterized by multinuclear (¹H, ¹³C, and ³¹P) NMR, IR spectroscopy and HRMS.     

Reduction of Sulfonylimines with Raney Nickel

Raney-Ni/EtOH reduction of different N-sulfonylimines provides a new entry for synthesizing sulfonamides in good yields under mild conditions. This protocol, which does not require additional hydrogen, constitutes a cheap, safe, and easy-to-handle alternative procedure to prepare α-branched sulfonamides.     

Highly Efficient Michael Addition Reaction of Amines Catalyzed by Silica-Supported Aluminum Chloride

Aliphatic and aromatic amines undergo smooth nucleophilic addition to α,β-unsaturated compounds in the presence of a catalytic amount of silica-supported aluminum chloride at 60 °C and under solvent-free conditions to produce the corresponding β-amino compounds in excellent yields. This method is simple and convenient and works efficiently under mild conditions. This catalyst can used again without losing its activity three times.     

Cu(II)-β-cyclodextrin-catalyzed synthesis of spiro[indoline-3,4′-pyrano[3,2-c]chromene]-3′-carbonitrile derivatives

Cu(II)-β-cyclodextrin-catalyzed synthesis of spiro[indoline-3,4′-pyrano[3,2-c]chromene]-3′-carbonitriles through the reaction of isatin derivatives, 4-hydroxycoumarin, and malononitrile in ethanol at room temperature.     

Overview on the phosphonation of the C=X functional groups utilizing alkyl phosphites

The main objective of this survey is to provide a comprehensive review of recent achievements related to the phosphonation processes, applying alkyl phosphites and different electrophiles (C?X, X: O, N, or C). The review discusses the important reactions of trialkyl and dialkyl phosphite reagents with a variety of aldehydes, ketones, aldimines, ketimines, hydrazones, oximes, diazo compounds, thio- and isocyanates as well as activated olefins as a convenient methodology for the synthesis of biologically important α-hydroxy- and α-aminophosphonates as well as heterocycles containing phosphorus and substituted heterocyclic phosphor esters. We are herein concentrating only on reactions that lead to phosphorylated products as they represent a vast and important research area of interest for academic, as well as for industrial, pharmaceutical and phytopharmaceutical chemists. The literature survey has been fully covered up by our group and others over the last 25 years.     

Organocatalyzed One-Pot Synthesis of Substituted 1,5-Benzodiazepine and Benzimidazole Derivatives

An efficient synthesis of some heterocycles is described by condensation between o-phenylenediamine and 1,3-dicarbonyl compounds catalyzed by L-proline. The reaction is carried out either at room temperature or reflux depending on the substrates.