Reduction of Aromatic α-Halo Ketones with Metallic Bismuth

Aromatic α-bromo ketones and α-iodio ketones can be reduced by bismuth prepared from NaBH₄ and BiCl₃ in water to their parent ketones in high yields, but aromatic α-chloro ketones should be added to sodium iodide first.     

One-Pot Synthesis of Pyrazolyl-Containing α-Aminophosphonates

Abstract

A series of novel pyrazolyl-containing α-aminophosphonates were synthesized by one-pot reaction from 4-formylpyrazole, substituted aromatic amines, and dialkylphosphites. The synthesized compounds were characterized by elemental analysis, ¹H NMR, and IR spectroscopy. Single-crystal X-ray diffraction data of compounds 4a and 5b were obtained, and some of these compounds showed inhibitory effect on eggplant-infecting Botrytis cinerea.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Tables S1-S4. Figures S1 and S2 .cif files.     

Regiospecific Synthesis of α-Alkylated Ketones

Several solutions have been developed to avoid the troublesome di- and polyalkylation encountered in ketone enolate alkylations¹, including use of the covalent Li enolate, or “additives” to tighten the metal-oxygen bond (M = Si^2,3,4, Sn^5,6, Al⁶, B^7,8,9).     

New and Stereospecific Synthesis of α-Ethylenic Ketones

Abstract

H. Kise et al¹ have shown that the reaction of β-propiolactones 1 with ylides 2 give phosphonium carboxylate betaïne 3. We now report that, carried out under different conditions, reaction of lactones 1 with the same ylides proceeds through pathway (b). Thermolysis of 4 affords α-ethylenic ketones 5. The mecanism of this new extrusion reaction of triphenylphosphine oxyde probably involves the generation of an oxaphosphene as an intermediate.     

Synthesis of New Thiazoles from α-Halohetaryl Ketones

Reactions of -bromoacetylphenoxathiin, -bromoacetylphenoxathiin 10,10-dioxide, or -bromoacetylthianthrene with certain p-(arylsulfonyl)thiobenzamides lead to the formation of the corresponding 2,4-disubstituted thiazoles. The new compounds were characterized through elemental analysis and spectral data (IR, ¹H NMR, and ¹³C NMR).     

Synthesis of α,β-Unsaturated Ketones via Enamines

Acylation of an enamine followed by acid hydrolysis constitutes the well-known Stork's reaction of synthesizing β-diketones.^1,2 This article reports that the acylated enamine 1 which corresponds to monoenamine of a β-diketone can be hydrogenated to a Mannich base 2 which on elimination by heating or treatment with acid yields the α, β-unsaturated ketone 3; further hydrogenation gives saturated ketone 4 in good yield (Scheme 1). A similar transformation effected by hydroboration has been reported by Montury and Góre.     

Highly Efficient One-Pot Synthesis of α-Aminophosphonates Catalyzed by Ytterbium Triflate in Water

A facile one-pot, three-component synthesis of α -aminophosphonates catalyzed by ytterbium triflate [Yb(OTf)₃] in water using polyoxyethanyl α -tocopheryl sebacate (PTS) as amphiphile has been developed. The catalytic system could be readily recycled and reused several times without significant loss in its activity.     

One-Pot Synthesis of α-Monosubstituted Pyridiniums from Corresponding Pyrylium Salts

Abstract

α-monosubstituted pyridiniums were readily prepared by the one-pot reaction of their corresponding pyrylium salts and primary amines. This result shows that such kind of pyridiniums can be prepared via this route. It was proved that the number of phenyl groups at the pyrylium ring had a crucial effect on this one-pot synthetic route.     

Synthesis of β-Amino Phosphonates in One-Pot Procedure

Abstract: β-amino phosphonate derivatives are synthesized in one-pot procedure via reduction of β-enamino phosphonate intermediates with NaBH₄/acetic acid or trifluoroacetic acid.     

A Facile Synthesis of Secondary α-Alkoxy or α-Acetoxy Aromatic Ketones

Abstract: The treatment of HNIB with aromatic ketones and subsequent solvolysis using alcohol or acetic acid in one-pot system makes it possible to give corresponding secondary α-alkoxy or α-acetoxy ketones in high yields.     

Synthesis of Potential Cytotoxic α-Methylene γ-Lactams

α-Methylene γ-lactones are known to have physiological activity, especially as cytotoxic agents, and are widely found in nature (1). However they are often toxic which makes them inappropriate for cancer treatment.     

One-Pot, Three-Component Coupling Approach to the Synthesis of α-Iminocarboxamides

A one-pot, three-component coupling was accomplished via the nucleophilic addition of an alkylsamarium(III) species to isocyanides and the subsequent addition of the resultant imidoyl samarium(III) species to isocyanates under mild conditions for the formation of α-iminocarboxamides. The developed sequential C-C bond-forming procedure enabled the rapid synthesis of the α-iminocarboxamides in good to excellent yields from readily available starting materials.     

Graphene Oxide as Recyclable Catalyst for One-Pot Synthesis of α-Aminophosphonates

We report the synthesis of α-aminophosphonates from aromatic aldehydes, aromatic and aliphatic amines, and trimethylphosphite (Kabachnik–Fields reaction) using a “carbocatalyst,” graphene oxide, at room temperature with excellent yield and recyclability. Enhanced catalytic activity of graphene oxide as compared to other catalysts studied is possibly due to the presence of carboxylic acid and hydroxyl groups.     

Tween-20: An Efficient Catalyst for One-Pot Synthesis of α-Aminophosphonates in Aqueous Media

Abstract

A green one-pot three-component synthesis has been developed for α-aminophosphonates by condensation of aldehydes, amines, and diethylphosphite by using nonionic surfactant Tween-20 as catalyst in aqueous media. The results showed that this synthetic route for α-aminophosphonates takes just 25–60 min for completion at 60 °C and affords 64%–91% yields depending on the nature of the amine substrates. The major advantages of this novel method are green reaction conditions with water as solvent, simple workup, less reaction times, and high to moderate yields.     

One-Pot Regioselective γ-Trifluoromethylthiolation and γ-Methylthiolation of Enals

We describe herein the direct electrophilic γ-trifluoromethylthiolation and γ-methylthiolation of enals, via the in situ formation of the corresponding silyl dienol ether. This one-pot process is carried out under simple and mild reaction conditions and is compatible with a variety of functional groups.     

Synthesis of Peroxy-Containing Acetylenic Alcohols and Ethers Derived from γ-Amino Ketones

A series of peroxy-containing tertiary alcohols were prepared by the reactions of lithium peroxy acetylenides with -amino ketones. The reactions of the intermediate lithium peroxy alcoholates with alkyl iodides in the presence of hexamethylphosphoramide yielded the corresponding peroxy ethers. The thermal stability of the compounds synthesized was evaluated by thermal analysis.     

Enantioselective De Novo Synthesis of α,α-Diaryl Ketones from Alkynes

Chiral α,α-diaryl ketones are structural motifs commonly present in bioactive molecules, and they are also valuable building blocks in synthetic organic chemistry. However, catalytic asymmetric synthesis of α,α-diaryl ketones bearing a tertiary stereogenic center remains largely unsolved. Herein, we report a catalytic de novo enantioselective synthesis of α,α-diaryl ketones from simple alkynes via chiral phosphoric acid (CPA) catalysis. A broad range of enolizable α,α-diaryl ketones are prepared in good yields and with excellent enantioselectivities. The described protocol also serves as an efficient deuteration method for the preparation of enantiomerically enriched deuterated α,α-diaryl ketones. Using the methodology reported, bioactive molecules, including one of the best-selling anti-breast cancer drugs, tamoxifen, are readily synthesized.     

A Novel Approach to Synthesis of α，β－Unsaturated Ketones

A new approach to the synthesis of α，β-unsaturated ketones from 1,2,3-trimethyl benzimidazolium salt via the condensation reaction with aldehydes followed by the addition reaction of Grignard reagents with quaternary C=N bond was provided.     

Convenient Electrochemical Method for the Synthesis of α-Bromo Alkyl Aryl Ketones

An electrochemical procedure for the effective α-bromination of alkyl aryl ketones in excellent yield has been reported. The simple experimental procedure, catalyst-free conversion, and excellent yield of monobrominated products are the advantages of this method.