Oxidations with solid potassium permanganate

Anaerobic oxidation of aldehydes to carboxylic acids under hydrothermal conditions

Examples of anaerobic oxidation of aldehydes in hydrothermal solutions are reported. The reaction using iron(iii) nitrate as the oxidant occurs under mild hydrothermal conditions and generates carboxylic acids in good yields. This method differs from previous studies which use atmospheric oxygen as the oxidant.

Cation Exchange Resin Supported Oxidation of Alkylbenzenes and Olefins using Potassium Permanganate†

Rapid and efficient oxidation of alkylbenzene side chains at the benzylic positions as well as oxidative cleavage of olefins with potassium permanganate in presence of solid polymeric cation exchange resins in good yields is reported.

The solid-phase oxidation of steroidal alkenes with potassium permanganate and metal salts

The oxidation of steroidal alkenes by potassium permanganate and metal salts in the solid phase gives epoxides with a stereochemistry that can differ from that obtained by the use of per-acids.

Chloramine-T-Mediated Oxidation of Benzylic Alcohols Using Indium(III) Triflate

The efficient oxidation of benzylic alcohols to carbonyl compounds was performed using chloramine-T and a catalytic amount of indium(III) triflate. The primary benzylic alcohols were converted to the corresponding aldehydes in a good yield, and the secondary benzylic alcohols were oxidized to ketones in a high yield. The optimized reaction conditions required 0.3 eq of indium(III) triflate and the use of acetonitrile as a solvent.

Ultrasound assisted the chemoselective 1,1-diacetate protection and deprotection of aldehydes catalyzed by poly(4-vinylpyridinium)hydrogen sulfate salt as a eco-benign, efficient and reusable solid acid catalyst

Poly(4-vinylpyridinium) hydrogen sulfate solid acid was found to be efficient catalyst for preparation of 1,1-diacetate using ultrasound irradiation at ambient temperature and neat condition. Deprotection of the resulting 1,1-diacetates were achieved using the same catalyst in methanol solvent under ultrasound irradiation at room temperature. This new method consistently has the advantage of excellent yields and short reaction times. Utilization of solvent free, simple reaction conditions, isolation, and purification makes this manipulation very interesting from an economic and environmental perspective. Further, the catalyst can be reused and recovered for several times.

Introduction of poly(4-vinylpyridinium) perchlorate as a new, efficient, and versatile solid acid catalyst for one-pot synthesis of substituted coumarins under ultrasonic irradiation

Poly(4-vinylpyridinium) perchlorate, is a supported, recyclable, eco-benign catalyst for synthesis of substituted coumarins via Pechmann reaction using ultrasound irradiation at room temperature and neat condition in high yields with short reaction times. The catalyst was studied by FT-IR, X-ray diffraction, scanning electron microscope, thermo-gravimetric and energy dispersion X-ray analyses. All the products were extensively characterized by (1)H NMR, FT-IR, MS and melting point analyses. This methodology offers momentous improvements over various options for the synthesis of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic catalysts and solvents. Further, the catalyst can be reused and recovered for several times without loss of activity.

An alternative solvent-free synthesis of nopinone under ball-milling conditions: Investigation of reaction parameters

A new method for the oxidative cleavage of β-pinene (1) yielding nopinone (2) with potassium permanganate as oxidant under solvent-free conditions was established. The reaction was performed in a conventional ball mill with use of a grinding auxiliary. The auxiliary has the ability to sorb liquid reactants such as 1 on its surface to make liquid(s) accessible for mechanical impact. Different reaction parameters and technical variables were assessed concerning their influence on yield and selectivity of 2. Different chemical parameters such as oxidants, grinding auxiliaries, and quantities were investigated. Also tuning parameters including milling time, rotation frequency, and number of milling balls were explored.

Experimental verification of diverging mechanisms in the binding of ether, thioether, and sulfone ligands to a dirhodium tetracarboxylate

Complexation of the oxygen atom in 2-butylphenylethers and sulfur in 2-butylphenylthioethers to a rhodium atom in dirhodium tetracarboxylate Rh((II)) (2)[(R)-(+)-MTPA](4) is compared. Oxygen atoms complex via electrostatic attraction exclusively leading to an increase in alpha effects on C-2 complexation shifts in the sequence OCH(3) > F > Br > NO(2). However, that trend is opposite in thioethers. This can be rationalized by an additional highest occupied molecular orbital (HOMO)-LUMO interaction and the response of this interaction upon complex formation shifts. Thereby, an experimental evidence was found for the existence of the HOMO-LUMO binding mechanism which has been proposed previously based on theoretical considerations and indirect spectroscopic evidence. Sulfones hardly bind to Rh((II)) (2)[(R)-(+)-MTPA](4). Diastereomeric dispersion effects at (13)C and (1)H signals can be observed for all compounds indicating that enantiodifferentiation is easy in all classes of functionalities.

Efficient Construction of Biaryls and Macrocyclic Cyclophanes via Electron-Transfer Oxidation of Lipshutz Cuprates

An efficient method for the homocoupling of aryl halides by electron-transfer oxidation of Lipshutz cuprates (Ar2Cu(CN)Li2) with organic electron acceptors is disclosed. Thus, various types of Lipshutz cuprates are prepared by successive treatment of aryl or heteroaryl bromides with tert-butyllithium and CuCN. The electron-transfer oxidation of Lipshutz cuprates with p-benzoquinones proceeds smoothly to afford the corresponding homocoupling products in moderate to good yields. Furthermore, it can be applied to the construction of either thiophene- or benzene-fused 10-membered ring cyclophanes. For the synthesis of 10-membered cyclophanes, the linear C-Cu-C structure of Lipshutz cuprates should be maintained in the dimetallacyclic intermediates, producing the large ring cyclophanes efficiently. The X-ray analysis of the cyclophanes reveals that the difference in the bridging atoms results in the different conformations of the macrocyclic rings. Thus, the silicon-bridged cyclophane 5a adopts a D2-symmetric structure with a twisted rhombic arrangement of four thiophene rings, whereas the methylene- and oxygen-bridged cyclophanes 5b and 5c possess C2h- and C2-symmetric structures with chair- and boatlike conformations, respectively. The 1H NMR spectrum of C2-symmetric 5c is temperature-dependent, and the activation energy (DeltaG) for the conformational change is 10.1 kcal/mol.

Carbonyl- and sulfur-containing analogs of suberoylanilide hydroxamic acid: Potent inhibition of histone deacetylases

Suberoylanilide hydroxamic acid (SAHA), an inhibitor of histone deacetylase, is used in clinical trials for a variety of advanced cancers. Twelve new analogs of SAHA were synthesized and tested as in vitro inhibitors of isolated histone deacetylases (HDACS) and in vivo inhibitors of interferon regulated transcriptional responses (a marker for HDAC activity). The analogs containing an alpha-mercaptoketone or an alpha-thioacetoxyketone were more potent than SAHA in both assays.

Synthesis of Bridgehead Hydroxy Bicyclo[2.2.2]octane Derivatives1

Two independent synthetic routes, starting from 1,3-cyclohexadione, toward the 4-hydroxy bicyclo[2.2.2]octane-2,6-dione derivative 3 are described.

Synthesis of side chain truncated 3"-aldehyde, 3"-carboxylic acid, and 1"-aldehyde from nodulisporic acid A

An efficient synthesis of the truncated 3"-aldehyde (3) from nodulisporic acid A (1) under mild conditions is described. Further oxidation of 3 to 3"-carboxylic acid (4) and its subsequent oxidative degradation produced 1"-aldehyde (5). These new derivatives are versatile intermediates for the preparation of new, side chain modified derivatives of nodulisporic acid A. [reaction: see text]