An efficient,one-pot,three-component procedure for the synthesis of chiral spirooxindolopyrrolizidines via catalytic highly enantioselective 1,3-dipolar cycloaddition

The catalytic, highly regio-, diastereo-, and enantioselective synthesis of a small library of chiral spirooxindolopyrrolizidines via a three-component 1,3-dipolar cycloaddition reaction of azomethine ylides, derived from isatin, with electron-deficient dipolarophiles, 3-(2-alkenoyl)-1,3-oxazolidin-2-ones, is described. A chiral copper(II) complex of cyclohexane-1,2-bis(arylmethyleneamine) catalyzed this process at room temperature. The reaction mechanism is discussed on the basis of the assignment of the absolute configuration of the cycloadducts.     

Practical highly enantioselective synthesis of propargylamines through a copper-catalyzed one-pot three-component condensation reaction

The one-pot three-component reaction of terminal alkynes, aldehydes and secondary amines in the presence of copper(I) bromide/quinap is reported. The reaction scope has been determined and a broad variety of all three components has been used, which afforded the corresponding propargylamines in good to excellent yields and moderate to very good enantioselectivities. The reaction showed a strong positive nonlinear effect. The transformation of a propargylamine intermediate into the alkaloid (S)-(+)-coniine has also been described.     

A highly diastereoselective, catalytic three-component assembly reaction for the synthesis of spiropyrrolidinyloxindoles

Spiropyrrolidinyloxindole compounds are synthesized in moderate to excellent yield via a highly diastereoselective Cu(I)-catalysed three-component assembly reaction of an imine, diazo-compound and substituted olefin dipolarophile.     

A one-pot, three-component synthesis of thiazolidine-2-thiones

An efficient method for the synthesis of thiazolidine-2-thiones is described via regiospecific iodocyclization of an allyl amine, carbon disulfide, and iodine. Dehydrohalogenation of the iodo-derivatives gives thiazole-2(3H)-thiones. In addition, nucleophilic substitution of the iodine in the products is accomplished using NaN₃, thiophenol, or dithiocarbamate.     

A simple and efficient highly enantioselective synthesis of alpha-ionone and alpha-damascone

An efficient highly enantioselective (ee > or =99%) synthesis of alpha-ionone and alpha-damascone is described. Both enantiomers of title compounds were synthesized through two straightforward pathways diverging from enantiopure (R)- or (S)-alpha-cyclogeraniol. These versatile building blocks were obtained by regioselective ZrCl(4)-promoted biomimetic cyclization of (6S)- or (6R)-(Z)-6,7-epoxygeraniol, respectively, followed by deoxygenation of the so formed secondary alcohol. The chiral information was encoded by a highly regioselecive Sharpless asymmetric dihydroxylation of inexpensive geranyl acetate.     

Palladium-catalyzed one-pot synthesis of highly substituted furans by a three-component annulation reaction

A new three-component cyclization-coupling reaction catalyzed by palladium was developed, producing polysubstituted furans in good yields from readily available substrates. The reaction conditions and the scope of the process were examined, and a possible mechanism is proposed.     

Stereoselective one-pot, three-component synthesis of 4-amidotetrahydropyran

The reaction of aldehyde with allylsilane in acetonitrile mediated by boron trifluoride etherate generated 4-aminotetrahydropyrans in good yields. The product is highly stereoselective.     

A highly enantioselective benzothiepine synthesis

A highly enantioselective synthesis of benzothiepine 1a has been accomplished via an enantioenriched sulfoxide intermediate obtained by asymmetric oxidation with a chiral oxaziridine in 89:11 er. The key step is a thermodynamically controlled asymmetric cyclization reaction that produces two new stereogenic centers. The (4R,5R) isomer 1a was obtained in 98:2 er.     

Enantioselective one-pot three-component synthesis of propargylamines

[reaction: see text] A copper(I) complex of i-Pr-pybox-diPh has been found to be an efficient catalyst for an enantioselective one-pot three-component synthesis of propargylamines from aldehydes, amines, and alkynes. The reaction has been applied to a wide variety of aromatic aldehydes with excellent yields (up to 99%) and enantiomeric excesses (up to 99% ee). A transition-state model has been proposed to explain the stereochemical outcome of the reaction.     

Copper-catalyzed three-component one-pot synthesis of quinazolines

Two efficient approaches to multi-substituted quinazolines by the three-component one-pot reaction of o-bromo aromatic ketones/aldehydes, ammonia water and aromatic aldehydes, or primary alcohols catalyzed by CuCl have been developed.     

A novel, one-pot and three-component synthesis of α-quinoxalinyl triphenylphosphoranes

The reactive 1:1 zwitterionic intermediate formed by the addition of triphenylphosphine to diaroylacetylenes was trapped with 1,2-benzenediamines to produce triphenylphosphorane intermediates. Intramolecular cyclization and subsequent oxidation of the intermediate afforded functionalized α-quinoxalinyl triphenylphosphoranes in good to excellent yields.     

A highly enantioselective catalytic intramolecular Stetter reaction

A family of chiral triazolium salts has been developed for inducing the asymmetric intramolecular Stetter reaction. The use of an aminoindanol-derived catalyst affords optimal results, with the product keto esters formed in 82-97% ee and very good chemical yield. Aromatic and aliphatic aldehydes are equally competent substrates for this reaction. The reaction conditions are reasonably mild and allow the isolation of the newly formed stereocenter without epimerization, although the presumed carbenic intermediates are strong bases.     

A highly enantioselective synthesis of cyclic alpha-amino acids involving a one-pot,single catalyst,tandem hydrogenation-hydroformylation sequence

Tandem enantioselective hydrogenation followed by a hydroformylation-cyclisation sequence leading to cyclic alpha-amino acids with ee's > 95% can be achieved in a single pot, one catalyst system by successive reactions of prochiral dienamide esters with H2 followed by H2/CO using Rh(I)-DuPHOS.     

Ketones in the catalytic three-component “one-pot” Kabachnik-Fields synthesis of α-amino phosphonates

Reactions of carbocyclic, heterocyclic, and steroidal ketones with benzylamine and diethyl phosphite in a catalytic three-component “one-pot” synthesis of α-amino phosphonates were studied. The activities of mono-and binuclear complexes of tetra(tert-butyl)phthalocyanines as catalysts for this process were compared. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1164–1169, July, 2006.     

A novel one-pot, three-component reaction for the synthesis of isocoumarin-condensed pyrazoles

The one-pot, three-component reaction of substituted homophthalic anhydrides with hydrazine in DMF as solvent and reactant, at reflux temperature, afforded isochromeno[3,4-c]pyrazole-5(2H)-one derivatives in high yields. The mechanism and roles of the substrates were investigated and it was found that cyclic hydrazides were formed as intermediates.