10339-61-4

Asymmetric nitrene-transfer reactions are a powerful tool for the preparation of enantioenriched amine building blocks. Reported herein are chemo- and enantioselective silver-catalyzed aminations which transform di- and trisubstituted homoallylic carbamates into [4.1.0]-carbamate-tethered aziridines in good yields and with ee values of up to 92 %. The effects of the substrate, silver counteranion, ligand, solvent, and temperature on both the chemoselectivity and ee value were explored. Stereochemical models were proposed to rationalize the observed absolute stereochemistry of the aziridines, which undergo nucleophilic ring opening to yield enantioenriched amines with no erosion in stereochemical integrity.

The low-valent nickel-catalysed coupling of Grignard reagents with 5-alkyl-2,3-dihydrofurans is an efficient and stereoselective method for synthesising homoallylic alcohols provided appropriate care is taken in the workup.

Chiral selenide-catalyzed oxytrifluoromethylthiolation of aliphatic internal alkenes by a formally intermolecular strategy is disclosed, affording CF3S 1,3-amino alcohol and 1,3-diol derivatives with high regio-, enantio-, and diastereoselectivities. The reactions are promoted by a neighboring imide or ester group on substrates via a six-membered ring transition state. This assistance strategy is also successfully applied to the regio- and diastereoselective oxyhalofunctionalization of internal alkenes and the conversion of alkynes.

The invention discloses a 2-carbonyl-1,3-oxazine compound and a preparation method therefor and application thereof. The structural formula of the 2-carbonyl-1,3-oxazine compound is shown in a formula II. The preparation method comprises: carrying out a reaction on a compound shown in a formula I and N-bromoacetamide (or 1,3-dibromo-5,5-dimethyl hydantoin) under the action of a scandium trifluoromethanesulfonate/monophosphine ligand. The photoactive 2-carbonyl-1,3-oxazine compound provided by the invention can be used for conveniently obtaining compounds containing 1,3-hydroxylamine structures and functionalized heterocyclic compounds through further conversion reactions, and meanwhile, a bromine atom can be introduced into the reaction. The functional groups can be further converted. Other functional groups are introduced, so that the compound has huge application value. According to the method provided by the invention, raw materials are easily synthesized, the reaction condition is mild, the operation is simple and convenient, the region selectivity is high, the enantioselectivty can reach up to over 99%, and the output reaches up to 72%. The formulae are shown in the description.

An indane-based, bifunctional, chiral selenide catalyst has been developed. The new catalyst is efficient for the enantioselective synthesis of saturated azaheterocycles possessing a trifluoromethylthio group. The desired products were obtained in good yields with high diastereo- and enantioselectivities.

The present application discloses novel PWNN and PWNWP metal catalysts for organic chemical syntheses including hydrogenation (reduction) of unsaturated compounds or dehydrogenation of substrates. The range of hydrogenation substrate compounds includes esters, lactones, enals, enones, enolates, oils and fats, resulting in alcohols, enols, diols, and triols as reaction products. The catalysts of current application can be used to catalyze a hydrogenation reaction under solvent free conditions. The present catalysts also allow the hydrogenation to proceed without added base, and it can be used in place of the conventional reduction methods employing hydrides of the main-group elements. Furthermore, the catalysts of the present application can catalyze a dehydrogenation reaction under homogenous and/or acceptorless conditions. As such, the catalysts provided herein can be useful in substantially reducing cost and improving the environmental profile of manufacturing processes for a variety of chemicals.

Catalyst tune-up: A readily available, air-stable amino-sulfide catalyst, [RuCl2(PPh3){HN(C2H4SEt) 2}], has been developed. This complex displays outstanding efficiency for the hydrogenation of a broad range of substrates with C-X bonds (esters, ketones, imines), as well as for the acceptorless dehydrogenative coupling of ethanol to ethyl acetate (see scheme). Copyright

There and back again: Hydrogenation of esters and the reverse reaction of dehydrogenative coupling of alcohols are efficiently catalyzed by dimeric complexes of Ru and Os under neutral conditions. The Os dimer (see picture) is an outstanding catalyst for the hydrogenation of alkenoates and triglycerides, and allows production of fatty alcohols from olive oil. This complex converts ethanol into ethyl acetate and hydrogen under reflux. Copyright

Treatment of hydrated RhCl3 and Cu(NO3)2 in THF and H2O with triethoxysilane affords a highly chemo- and stereoselective catalyst system for the reduction of alkynes to Z-alkenes while alkyl-NO2, aryl-NO2, N-carbobenzyloxy, hydroxy, ester, enoate, benzyloxy, alkyl bromide, aryl bromide, and enone moieties remain unaffected.

The reactions of (silylmethyl)cyclopropanes with haloboranes, such as BBr3 and BHBr2, result in desilylative ring opening to give homoallylboranes and boracyclopentanes, respectively.Coupled with subsequent oxidation procedure, these reactions provide ready access to homoallylic alcohols and 1,4-diols.

Extremely high selectivity was provided by calcium in liquid ammonia in the cleavage of the benzylic carbon-oxygen bond in benzyl ethers containing various other functionalities.Results of controlled experiments indicate that the selectivities offered by the Ca -> Ca+ + e- and the Ca+ -> Ca2+ + e- processes are 4.6 and 47 times greater, respectively, than that afforded by the Li -> Li+ + e- process.

Wittig-reaction intermediates derived from hexanal and (γ-oxidopropylidene)triphenylphosphorane, (1), are freely reversible, as indicated by significant quantities of cross-over products from a second aldehyde (octanal); such a result may account for anomalously enhanced E stereoselectivity in the reaction of γ- and β-oxido ylides with aliphatic aldehydes.

The reaction of aldehydes with oxido ylides shows a dramatic dependence of alkene stereochemistry on the distance between oxygen and phosphorus atoms; ylides with proximal O and P atoms favor production of E alkenes.The high E stereoselectivity with γ-oxido ylides is not mainly attributable to intramolecular proton-exchange in a Wittig intermediate.

Dimethylaluminum chloride, which is a mild Lewis acid and a proton scavenger, catalyzes the ene reactions of aliphatic and aromatic aldehydes with alkenes containing a disubstituted vinylic carbon. Proton-initiated rearrangements do not occur, since the alcohol-Lewis acid complex formed in the ene reaction reacts rapidly to give methane and a nonacidic aluminum alkoxide. Formaldehyde and excess Me//2AlCl give good yields of ene adducts with all types of alkenes. With 1 equiv of Me//2AlCl, formaldehyde and mono- and 1,2-disubstituted alkenes give gamma -chloro alcohols resulting from cis addition of chlorine and hydroxymethyl groups to the double bond. This work is pertinent to the synthesis of alcohols.