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Application of 1-bromooctane fails to give a product of carbonylative coupling yielding 1-cyanooctane instead.

I2-catalyzed oxo-acyloxylation of alkenes and enol ethers with carboxylic acids providing for the high yield synthesis of α-acyloxyketones and esters is described. This unprecedented regioselective oxidative process employs TBHP and Et3N in stoichiometric amounts under metal-free conditions in DMSO as solvent. Additionally, I2-catalysis allows the direct hydroxy-acyloxylation of alkenes with the sequential addition of BH3·SMe2 leading to monoprotected diol derivatives in excellent yields.

The synthesis of anti-alcohols (III) and syn-alcohols (VI) is carried out by a phenolic kinetic resolution of corresponding epoxides (I) and (V) in the presence of a chiral cobalt salem catalyst.

Treatment of aldehydes with sulfur ylide (CH2=SOMe2 or CH2=SMe2), in the presence of CO2 (1 atm) bubbled sequentially under mild conditions, produces cyclic carbonates in preparative yields. Sodium iodide formed in situ promotes the reaction between epoxide as intermediate and CO2 at ambient conditions, thus constituting a powerful metal-free synthesis of organic cyclic carbonates directly from aldehydes.

An efficient synthesis of the 2,3-disubstituted piperidines (+)-L-733,060 and (2 S ,3 S )-3-hydroxypipecolic acid (≥99% ee) in high optical purity from commercially available starting materials is described. The strategy involves a cobalt-catalyzed hydrolytic kinetic resolution of a racemic azido epoxide with two stereocenters and an intramolecular reductive cyclization as key reactions.

To ensure reliable operation of Power transformer, condition monitoring of transformer becomes obligatory. In this paper, condition assessment of transformer oil under various working conditions is performed using UV-visible spectrophotometer. Test samples include both laboratorial prepared ones and those obtained from in service transformers. An index table of spectral responses for various faults which predominantly occur in the transformer is developed. The index table will acts as a reference for spectral response of faulted transformer oil. In this paper, an attempt has been made to determine the quality of transformer oil using their spectral response characteristics.

Communication: The living radical polymerization of 4acetoxystyrene via the RAFT process has been achieved employing bulk, solution and emulsion techniques. The rate of polymerization was studied between 608C and 908C. Increasing the temperature increases the rate of polymerization without affecting the polydispersity. Poly(4-acetoxystyrene) with narrow polydispersity (1.08) was obtained. Various novel dithiocarboxylic esters and dithiocarbamates were screened as chain-transfer agents for the RAFT polymerization of 4-acetoxystyrene. The block copolymerization of poly(4-acetoxystyrene) with styrene leading to poly(4-acetoxystyrene)-block-polystyrene confirmed the presence of active chain ends in the first block. The acetoxy polymers were hydrolyzed to the corresponding hydroxy polymers under mild basic conditions.

The addition of thiols and thiobenzoic acids onto olefins proceeded regioselectively in a Markovnikov manner in the presence of Montmorillonite K 10 (Mont K 10) clay as the catalyst to afford thioethers and thiocarboxylic S-esters, while high selectivity to anti-Markovnikov products was realized in the absence of any catalyst. Treatment of the esters with Lawesson's reagent provided the corresponding dithiocarboxylic esters in high yields.

A matrix-bound superoxide radical anion, generated by treating Ti(OR)4 (R=iPr, nBu) with H2 O2 , is a selective heterogeneous catalyst for the oxidation of anilines to the corresponding nitroarenes with 50 % aqueous H2 O2 [Eq. (1)]. Yields of 82-98 % are obtained, even with anilines bearing electron-withdrawing substituents (R=NO2 , COOH).

A new milder protocol for aziridination of a variety of olefins has been described. The process employs catalytic amount of sodium metaperiodate (NaIO 4 ) as an oxidant and LiBr and chloramine-T as the bromine and nitrogen sources, respectively. Interestingly, the formation of aziridine products in all the cases studied takes place presumably through a process of 1,2-aminobromination of alkenes.

A high-yielding enantioselective synthesis of the bioactive (S)-N-(5-chlorothiophene-2-sulfonyl)-β,β-diethylalaninol (1), a Notch-1-sparing γ-secretase inhibitor metabolite (with EC50 = 28 nM) effective in reduction of Aβ production in vivo, has been realized starting from readily available 3-pentanone. The key steps of the synthesis are proline-catalyzed α-aminooxylation and α-amination of aldehyde; the latter contributing an overall yield of 45.2% and 98% ee.

Macrocyclic Ni(II) complex, 1, catalyzes efficiently the chemoselective transfer reduction of carbonyl compounds in presence of propan-2-ol / KOH or HCO2H / HCO2NH4 as hydrogen donors to produce the corresponding alcohols in high yield.

(2000). RECENT ADVANCES IN CLAY-CATALYZED ORGANIC TRANSFORMATIONS. Organic Preparations and Procedures International: Vol. 32, No. 1, pp. 1-40.

A new facile procedure for the aminobromination of olefins in high yields has been described using p-toluene sulfonamide (p-TsNH2) and N-bromosuccinimide (NBS) as nitrogen and bromine sources, respectively, and titanium superoxide as a truly heterogeneous catalyst. The formation of anti-Markovnikov product exclusively in all the cases studied possibly proceeding through a free radical reaction pathway is remarkable.

Mg-Al Hydrotalcite (HT) has been found to catalyze the reaction between aldehydes and nitroalkanes very efficiently affording threo nitroalkanols in a highly diastereoselective manner. The ratios of threo erythro isomers are determined from their respective 13C-NMR spectra. A mechanism based on the transition state model for the predominant formation of threo-isomers is also described.

Dihydro-4,4-dimethyl-2(3 H )-furanone 6 , the key intermediate to ( R )-pantolactone 2 , has been synthesized in two steps via the radical cyclization of bromoether 5 . Silyl enol ether 7 , prepared from 6 , on Sharpless asymmetric dihydroxylation gave ( R )-pantolactone 2 in moderate yield and excellent enantioselectivity.

A mild and efficient catalytic method for the benzylic oxidation of alkyl arenes to the corresponding tert. butyl aryl peroxides is described using a catalytic amount of reusable solid, RuIII-exchanged Montmorillonite K10 and 70% tert. butyl hydroperoxide (TBHP) as oxidant.

The NaIO 4 –KI–NaN 3 combination has been found to be an efficient, reliable, and inexpensive reagent system for mono- and 1,2-difunctionalization of hydrocarbons via C–H bond activation to afford vicinal azido- and acetoxy iodinations of cyclic hydrocarbons.

A short and high yielding enantioselective synthesis of (−)-bestatin, a naturally occurring aminopeptidase inhibitor, is described via l -proline-catalyzed asymmetric α-amination of 3-phenylpropionaldehyde as the key reaction. The methodology also involves a Pd-catalyzed intramolecular cyclization of an allylic acetate giving a trans-oxazoline in a highly diastereoselective manner (dr > 14:1).

A short and efficient enantioselective synthesis of (+)-L-733,060 in 92% ee via Shi epoxidation of a homoallylic carboxylate is described. Johnson–Claisen rearrangement was employed to obtain the required carbon backbone, whilst intramolecular reductive O-to-N-ring expansion of a δ-azidolactone was used in the construction of the piperidine moiety.

A concise route to the asymmetric synthesis of (S)-vigabatrin® and (S)-dihydrokavain has been described using Co-catalyzed hydrolytic kinetic resolution of racemic epoxides and regiospecific opening of terminal epoxides with dimethylsulfonium methylide as the key steps.

Metal-exchanged clays (M = Rh and Cu) catalyze effectively the reaction of methyl diazoacetate with various aldehydes, affording the corresponding β-keto esters in high yields. They have also been effective in the decomposition of methyl diazoacetate to form metallocarbenes which, in turn, successfully insert into X–H (X = N, O, S, CO2) bonds of a variety of amines, aldehydes, thiols and acids, thereby producing the corresponding esters.

Regioselective alkylation of phenol with cyclopentanol is achieved over Montmorillonite K10 clay, producing 2-cyclopentylphenol, the key intermediate. The synthesis of optically active (S)-penbutolol 1, an important antihypertensive drug, is realized in 5 steps from 2-cyclopentylphenol by employing Sharpless asymmetric dihydroxylation.

An organocatalytic route to the synthesis of the atorvastatin side-chain, a building block present in the statin family, is described using l -proline-catalyzed α-aminooxylation of an aldehyde. The method also employs an iodine-induced intramolecular electrophilic cyclization of a carbonate to produce the iodocarbonate in a highly diastereoselective manner.

Osmium tetroxide catalyzed asymmetric aminohydroxylation of silyl enol ethers using cinchona alkaloids as chiral ligands and chloramine-T as the nitrogen source affords enantiomerically pure α-amino ketones.

Transesterification and transthiolesterification of β-keto esters with variety of alcohols and thiols and selective protection of carbonyl functions with various protecting groups catalyzed by natural kaolinitic clay are described. The clay has been found to be an efficient catalyst in transesterifying long chain alcohols, unsaturated alcohols, and phenols to give their corresponding β-keto esters in high yields. For the first time, transthiolesterification of β-keto esters with a variety of thiols has been achieved under catalytic conditions. Clay also catalyzes selective transesterification of β-keto esters by primary alcohols in the presence of secondary and tertiary alcohols giving corresponding β-keto esters. A systematic study involving the reactivity of different nucleophiles (alcohols, amines, and thiols) toward β-keto esters is also described. Sterically hindered carbonyl groups as well as α,β-unsaturated carbonyl groups underwent protection without the deconjugation of the double bond. Chemosele...

Natural kaolinitic clay efficiently catalyses the transdithioacetalization of acetals, ketals, oximes, enamines and tosylhydrazones with ethane-1,2-dithiol and propane-1,3-dithiol to produce the corresponding dithiolanes in high yields.