Samarium(II) iodide reduction of isoxazolidines

SmI₂ was used as reducing agent for the N-O bond cleavage in isoxazolidines. The procedure revealed is general and particularly useful for the transformation of 5-spirocyclopropane isoxazolidines to the corresponding β-aminocyclopropanols, a troublesome transformation with other known reagents.     

The use of formamidine protection for the derivatization of aminobenzoic acids

N,N-Dimethylformamidine and novel N,N-diisopropylformamidine protecting groups were used to carry out a one-pot conversion of aminobenzoic acids into the corresponding amides. General conditions for an in situ transformation of aminobenzoic acids and their heterocyclic analogues into the corresponding formamidine-protected acid chlorides were developed. These chlorides were used in reactions with amines, including poorly reactive anilines. The protected amides were then smoothly deprotected by heating with ethylenediamine derivatives, resulting in a general procedure for the one-pot transformation of aminobenzoic acids into their amides. Our one-pot procedure was successfully applied to the preparation of several compounds of pharmaceutical interest.     

Reductive Chlorination and Bromination of Ketones via Trityl Hydrazones

A method is presented for the direct transformation of a ketone to the corresponding reduced alkyl chloride or bromide. The process involves the reaction of a ketone trityl hydrazone with tBuOCl to give a diazene which readily collapses to the α‐chlorocarbinyl radical, reduction of which by a hydrogen atom source gives the alkyl chloride product. The use of N‐bromosuccinimide provides the corresponding alkyl bromide. This unique transformation provides a reductive halogenation that complements Barton's redox‐neutral vinyl halide synthesis.     

Reactions of vinylidenecyclopropanes with diphenyl diselenide in the presence of AIBN and further transformation to produce new naphthalene derivatives

The reactions of vinylidencyclopropanes 1 with diphenyl diselenide 2 in the presence of AIBN produced the corresponding products 4 or 5 in moderate to good yields under mild conditions. The transformation of 4 to the corresponding methylenecyclopropanes 6 was achieved by treatment with hydrogen peroxide (H2O2) in toluene, and these were further transformed to the corresponding naphthalene derivatives 7 by treatment with 30 mol % of TfOH in dichloromethane.     

Rh-catalyzed one-pot and practical transformation of aldoximes to amides

Wilkinson's complex has been found to catalyze the one-pot transformation of aldoximes to the corresponding amides with high selectivity and efficiency under essentially neutral conditions.     

Ring-opening reactions of diarylvinylidenecyclopropanes by iodine and bromine

Diarylvinylidenecyclopropanes undergo a novel ring-opening reaction upon treatment with iodine or bromine at 0-25 °C in 1,2-dichloroethane to give the corresponding iodinated or brominated naphthalene derivatives in good to high yields within 3 h. The further transformation of the corresponding iodinated or brominated naphthalene derivatives has been disclosed.     

Mechanism of meerwein-pondorf-verley type reductions

The reduction of benzophenone by lithium and chloromagnesium alkoxides has been studied as well as the transformation of certain lithium alkoxides to the corresponding ketones by electron transfer. Fluorenone was reduced by lithium sec-butoxide to the corresponding lithium ketyl to the extent of 65%. Lithium 9-fluoroenolate underwent in tetrahydrofuran a spontaneous transformation to lithium fluorenone ketyl. This process was interpreted as involving 1,2-hydrogen shift in an oxygen-centred radical. A mechanism for the Meerwein-Pondorf-Verley-type reductions is proposed, invoking single electron as well as 1,2-hydrogen shift steps.     

Aerobic oxidative transformation of primary azides to nitriles by ruthenium hydroxide catalyst

In the presence of an easily prepared supported ruthenium hydroxide catalyst, Ru(OH)(x)/Al(2)O(3), various kinds of structurally diverse primary azides including benzylic, allylic, and aliphatic ones could be converted into the corresponding nitriles in moderate to high yields (13 examples, 65-94% yields). The gram-scale (1 g) transformation of benzyl azide efficiently proceeded to give benzonitrile (0.7 g, 90% yield) without any decrease in the performance in comparison with the small-scale (0.5 mmol) transformation. The catalysis was truly heterogeneous, and the retrieved catalyst could be reused for the transformation of benzyl azide without an appreciable loss of its high performance. The present transformation of primary azides to nitriles likely proceeds via sequential reactions of imide formation, followed by dehydrogenation (β-elimination) to produce the corresponding nitriles. The Ru(OH)(x)/Al(2)O(3) catalyst could be further employed for synthesis of amides in water through the transformation of primary azides (benzylic and aliphatic ones) to nitriles, followed by sequent hydration of the nitriles formed. Additionally, direct one-pot synthesis from alkyl halides and TBAN(3) (TBA = tetra-n-butylammonium) could be realized with Ru(OH)(x)/Al(2)O(3), giving the corresponding nitriles in moderate to high yields (10 examples, 64-84% yields).     

Syn-selective vinylogous Kobayashi aldol reaction

The Kobayashi aldol reaction has become a prominent transformation in polyketide syntheses. This methodology takes advantage of the directing effects of the Evans auxiliary and allows the stereoselective incorporation of a four carbon segment with two additional methyl branches establishing an anti-relationship between the two newly formed chiral centers. So far this transformation was restricted to anti-aldol products. We present here a modified protocol that provides the corresponding aldol product with high syn-selectivity.     

Synthesis of ‘Pear Ester’. A novel synthesis of 2,4-diolefinic aldehydes and esters

Vinylogous epoxyaldehydes undergo stereospecific Wittig condensations in high yields. The resulting diolefinic epoxides are cleaved at the C(1)–C(2) single bond, when treated with periodic acid, to give the corresponding aldehydes. Direct transformation into the corresponding ethyl-ester leads to an efficient synthesis of the ‘pear ester’.     

Radical/Cation Transformation Polymerization and Its Application to the Preparation of Block Copolymers

Abstract

ESR study on the primary radicals obtained by decomposition of azo-compounds showed that primary radicals with electron donating substituents were transformed to the corresponding cations in the presence of electron acceptors such as ph₂I⁺PF^? ₆. Accordingly, propagating radicals are transformed to the corresponding cations in the polymerization of p-methoxy-styrene (MOS), n-butyl vinyl ether (BVE), and N-vinylcarbazole (VCZ) with azoinitiators such as AIBN in the presence of electron acceptors such as Ph₂I⁺PF^? ₆. In the case of BVE, the polymer formation was caused by cationic species produced by the transformation of the initiating radical. The polymerizations of MOS and VCZ were ascribed to the transformation of the growing radical to the corresponding cation during the propagation step which was classified as the radical/cation transformation polymerization. Block copolymers of MOS/cyclohexene oxide (CHO) and VCZ/CHO were effectively prepared by the radical/cation transformation polymerization of the appropriate monomers in the presence of AIBN, electron acceptor and CHO. The formation of block copolymers was characterized by turbidimetry, thin-layer chromatography, and solubility tests.     

Ruthenium- and Copper-Catalyzed Propargylic Substitution Reactions of Propargylic Alcohol Derivatives with Hydrazones

Ruthenium- and copper-catalyzed propargylic substitution reactions of propargylic alcohol derivatives with N-monosubstituted hydrazones as ambident nucleophiles are achieved in which N-monosubstituted hydrazones exhibit impressive different reactivities depending on different catalytic systems, behaving as carbon-centered nucleophiles to give the corresponding propargylic alkylated products in ruthenium catalysis, or as nitrogen-centered nucleophiles to afford the corresponding propargylic aminated products in copper catalysis. DFT calculations were carried out to investigate the detailed reaction pathways of these two systems. Further transformation of propargylic substituted products affords the corresponding multisubstituted pyrazoles as cyclization products in good to high yields.     

A mild One-Step Procedure for the Synthesis of β-Iodo Epoxides from the Corresponding Epoxy-Alcohols

The zinc salt-modified Mitsunobu halogenation was applied to the direct transformation of diverse epoxy-alcohols into the corresponding iodomethyloxiranes.     

Cyclization of Olefinic Benzyl Ethers with Aryltellurium Trichlorides

Olefinic benzyl ethers react with aryltellurium trichlorides leading to tetrahydrofurans in high yields. The reaction times and yields are similar to the analogous cyclization of the corresponding olefinic alcohols. The stereoselec-tivity of the transformation is low.     

Terminal olefins from aldehydes through enol triflate reduction

The transformation of aldehydes into terminal olefins through reduction of the corresponding enol triflates is described. The method is effective with both linear and alpha-branched aldehydes.     

A convenient scalable one-pot conversion of esters and Weinreb amides to terminal alkynes

Esters and amides undergo reduction to the corresponding aldehydes using DIBAL-H followed by same pot conversion to terminal alkynes utilizing the Bestmann-Ohira reagent in good to excellent yields. Additionally chiral nonracemic substrates undergo this transformation with complete preservation of stereochemical integrity.     

Determination of the Diffusion Coefficient for SDS Micelle with Different Shape and the Effects of Ethanol by Cyclic Voltammetry Without Probes

Micelle diffusion coefficient of SDS with different micelle shape in aqueous and water-ethanol solutions are determined by cyclic voltammetry without any probe. The diffusion coefficient decreases with as increasing SDS concentration. The first critical micellar concentration is 8.0xl0³, mol 1¹.corresponding to the transformation from premicelle to spherical micelle. The second critical micellar concentration is 5.60x10²and corresponding to transformation from spherical micelle to rod-like micelle. The less the weight ratio of SDS to ethanol is, the larger the diffusion coefficient is. The influence of added water to the micelle solution is almost the same for SDS-ethanol-HaO system with different micelle shape. Mechanism of electrochemical reaction for SDS at platinum electrode is discussed as well.     

Scalable synthesis of the VEGF-R2 kinase inhibitor JNJ-17029259 using ultrasound-mediated addition of MeLi-CeCl3 to a nitrile

The preparation of the selective VEGF-R2 kinase inhibitor 10 (JNJ-17029259) is described in which the key precursor, 4-(5-isoxazolyl)benzonitrile, undergoes clean transformation to the corresponding cumylamine derivative with CeCl(3)-MeLi in THF. This high-yielding cerium mediated transformation is robust, reproducible, and readily scalable based on a requirement for the anhydrous CeCl(3) to be milled and subjected to ultrasound treatment prior to addition of methyllithium.     

The mono-alkyldecyanation of tetrafluoroterephthalonitrile by reaction with Grignard reagents

Treatment of tetrafluoroterephthalonitrile in THF with alkyl Grignard reagents gives the corresponding 4-alkyltetrafluorobenzonitrile in about 60% yield. The scope and limitations of this transformation are reported.     

A new reactivity pattern for vinyl bromides: cine-substitution via palladium catalysed C-N coupling/Michael addition reactions

Palladium catalysed C-N bond formation can be used to convert vinyl bromides to the corresponding enamines, which are reacted in situ with alkylidene malonates to provide Michael adducts. The overall transformation results in cine-substitution of the starting vinyl bromide.