Chiral Pd aqua complex-catalyzed asymmetric C–C bond-forming reactions: a Brønsted acid–base cooperative system
Chiral cationic Pd aqua complexes can function as acid–base catalysts to give chiral Pd enolates with the concomitant formation of a protic acid. Cooperative action of the chiral Pd enolates with the protic acid to activate electrophiles is important to promote various C–C bond-forming reactions smoothly in a highly enantioselective manner.
Mass spectrometric screening of chiral
catalysts and catalyst mixtures
The use of quasi-enantiomeric substrates and ESI-MS makes it possible to determine the intrinsic enantioselectivity of chiral catalysts by monitoring catalytic intermediates, using a fast, operationally simple protocol.
addition reactions of arylboronic acids with alkyl 2-formylbenzoates: efficient access to chiral 3-substituted phthalides
Transition metal-catalyzed addition of arylboronic acids to 2-formylbenzoates afforded 3-substituted phthalides. By using SPINOL-based phosphites as ligands, a Rh(I)-catalyzed asymmetric version of such an addition reaction has been realized and up to 83% ee was achieved.
Total synthesis of
(+)-scyphostatin featuring an enantioselective and highly efficient route to the side-chain via Zr-catalyzed asymmetric carboalumination of alkenes ( ZACA)
An enantioselective ZACA route to the side-chain 3 permits an efficient and convergent synthesis of (+)-scyphostatin (1).
Diastereoselective and enantioselective Mukaiyama aldol reactions of α-ketoesters using
hydrogen bond catalysis
Hydrogen bond catalyzed Mukaiyama aldol reactions of α-ketoesters proceed in high diastereo- and enantioselectivities, giving products possessing two chiral centers, of which one is a tertiary alcohol.
Use of achiral additives to increase the stereoselectivity in
We describe our studies on the effect of various Lewis bases and Brønsted acids as achiral additives on the stereoselectivity of some Rh(II)-catalyzed cyclopropanations.
Rhodium-catalyzed dehydrogenative borylation of cyclic alkenes
A rhodium-catalyzed dehydrogenative borylation of cyclic alkenes is described. This reaction provides direct access to cyclic 1-alkenylboronic acid pinacol esters, useful intermediates in organic synthesis. Suzuki–Miyaura cross-coupling applications are also presented.
Gold(I)-catalysed cycloisomerisation of 1,6-enynes into functionalised allenes
1,6-Enynes can be cycloisomerised into allenes under gold catalysis. This transformation involves a 5-exo dig cyclisation followed by 1,5-hydride shift.
One pot ‘click’ reactions: tandem enantioselective biocatalytic
epoxide ring opening and [3+2] azide alkyne cycloaddition
Halohydrin dehalogenase can perform enantioselective azidolysis of aromatic epoxides to 1,2-azido alcohols which are ligated to alkynes producing chiral β-hydroxy-triazoles in a one-pot procedure with excellent enantiomeric excess.
Cross-couplings between benzylic and aryl halides “on
water”: synthesis of diarylmethanes
Diarylmethanes are made “on water” simply upon mixing, in water: reactants, catalyst, and a touch of TMEDA, at room temperature. Voila.
Synthesis of 3-hydroxyoxindoles by
Pd-catalysed intramolecular nucleophilic addition of aryl halides to α-ketoamides
Pd/PtBu3-catalysed intramolecular nucleophilic addition of aryl halides to α-ketoamides in the presence of nBuOH and base has been realized with high yields, providing a new, direct, and efficient synthetic strategy to obtain 3-hydroxyoxindoles.
Pd-catalyzed cascade carbopalladation-annulation reaction of 3-(2-iodobenzyl)-indoles into fused 6/5/7/6- and 6/5/5/6- heterocyclic systems
Polycyclic indole structures, possessing fused seven-membered rings were efficiently synthesized via the Pd-catalyzed intramolecular carbopalladation-annulation of 3-(2-iodobenzyl)-indoles with alkynes.
hydrogenation of α-aryl-β-substituted acrylic acids catalyzed by Ir-SpinPHOX
The enantioselective hydrogenation of a series of challenging substrates, α-aryl-β-substituted acrylic acids, was realized with high efficiency and enantioselectivity (up to 96%) under the catalysis of Ir(I) complex of Spiro-based P,N ligand, SpinPHOX.
Subtleties in asymmetric
catalyst structure: the resolution of a 6-phospha-2,4,8-trioxa- adamantane and its applications in asymmetric hydrogenation catalysis
Resolution of a C1-symmetric phospha-adamantane which has the diamondoid structure shown has been achieved and, surprisingly, its Rh complex is a selective asymmetric hydrogenation catalyst.
enantioselective synthesis of axially chiral allenes under thermal and microwave-assisted conditions
Silver(I) salts mediated stereospecific transformation of optically active propargylamines to axially chiral allenes with excellent enantioselectivities (17 examples with 96–99% ee; one substrate with 91% ee) without subsequent racemization.
Chiral bifunctional phase transfer
catalysts for asymmetric fluorination of β-keto esters
Chiral bifunctional phase transfer catalysts introducing bis(diarylhydroxymethyl) substituents at 3,3′-positions of the chiral binaphthyl core were successfully applied to asymmetric fluorination of cyclic β-keto esters with high enantioselectivities.
Stereoselective synthesis of trans-β-lactams by
palladium-catalysed carbonylation of vinyl aziridines
The palladium-catalysed carbonylation of vinyl aziridines can give either trans- or cis-β-lactams preferentially or even the δ-lactam simply by adjusting the reaction parameters ([Pd], [CO], temperature).
Palladium-catalyzed [ 3C + 2C + 2C] cycloaddition of enynylidenecyclopropanes: efficient construction of fused 5-7-5 tricyclic systems
A Pd-catalyzed intramolecular [3C + 2C + 2C] cycloaddition between alkylidenecyclopropanes, alkynes and alkenes is reported. The method provides synthetically relevant 5-7-5 tricyclic structures, with good chemoselectivity and complete diastereoselectivity.
Organocatalytic asymmetric Povarov reactions with 2- and 3-vinylindoles
The organocatalytic asymmetric Povarov reaction of N-arylimines with 2- and 3-vinylindoles has been developed. The peculiar reactivity of vinylindoles allowed the disclosure of versatile reaction manifolds for the preparation of highly enantioenriched indole derivatives.
cycloaddition of functionalized ketoenynes: synthesis of (+)-orientalol F
The synthesis of (+)-orientalol F has been completed by a stereoselective gold-catalyzed [2 + 2 + 2] cycloaddition of a ketoenyne, in which the propargylic stereocenter controls the formation of three additional stereocenters.
Highly enantioselective hetero-
Diels–Alder reactions between Rawal’s diene and aldehydes catalyzed by chiral dirhodium(II) carboxamidates
Rh2(S-BPTPI)4 is an exceptionally effective catalyst for enantioselective hetero-Diels–Alder reactions between Rawal’s diene and a diverse range of aldehydes to give, after treatment with acetyl chloride, dihydropyranone derivatives in good yields and with excellent enantioselectivities.
Iron-catalyzed addition of
Grignard reagents to activated vinyl cyclopropanes
The iron-catalyzed addition of Grignard reagents to activated vinyl cyclopropanes proceeds in a highly regioselective fashion for branched primary, secondary and tertiary alkyl Grignard reagents. The observed selectivity likely results from a direct addition mechanism as opposed to single electron transfer or an iron-allyl based process.
γ-Agostic interactions stabilize the propagating species in the vinyl addition polymerization of norbornene
Cationic [(tmeda)Pd(OEt2)(Me)][B(ArF)4] was synthesized and allowed for the first time the nature of the propagating species in the vinyl addition polymerization of norbornene to be discerned. In this system γ-agostic interactions stabilize the propagating species and permit stepwise monomer insertions to be observed by 1H NMR spectroscopy.
Copper-catalyzed arene C–H bond cross-coupling
A highly regioselective, one-pot sequential iodination–copper-catalyzed cross-coupling of arene C–H bonds has been developed affording an efficient method for biaryl synthesis.
Regioselective synthesis of halohydrin
esters from epoxides: reaction with acyl halides and rhodium-catalyzed three-component coupling reaction with alkyl halides and carbon monoxide
Regioselective synthesis of halohydrin esters was achieved by (1) the reaction of acyl halides with epoxides and (2) the rhodium-catalyzed three-component coupling reaction of alkyl halides, carbon monoxide, and epoxides.
Solid-phase synthesis of protected α-amino phosphonic acid oligomers
By establishing both a highly efficient phosphonamidate formation and a RuCp-catalyzed cleavage of an allyl linker, the solid-phase synthesis of Fmoc-(GlyP(OBn))6-OH/DIEA, a protected form of a new type of unnatural peptide α-amino phosphonic acid oligomer (APO), has been realized.
Palladium-catalyzed aryl halide carbonylation–intramolecular O-enolate acylation: efficient isocoumarin synthesis, including the synthesis of thunberginol A
Balloon pressure of CO is sufficient to efficiently convert a series of α-(o-haloaryl)-substituted ketones to the corresponding isocoumarins under the action of palladium catalysis.
Getting the sterics just right: a five-coordinate iridium trisboryl complex that reacts with C–H bonds at room temperature
Synthesis of five-coordinate boryl complexes that react directly with arenes at ambient temperature provides the first glimpse of the fundamental step in Ir-catalyzed C–H borylation.
cyclisation of N-allylacetamides with aryl halides yielding benzyl-substituted oxazolines
Treatment of N-allylacetamide with aryl halide in the presence of sodium t-butoxide and a palladium catalyst leads to arylative cyclisation to provide the corresponding benzyl-substituted oxazoline in high yield.
4-Substituted oxazolines, which are readily synthesized from naturally occurring α-amino acids, are converted efficiently and stereospecifically to β-amidoaldehydes in the presence of synthesis gas and catalytic dicobalt octacarbonyl.
Metal-catalyzed rearrangement of enantiomerically pure alkylidenecyclopropane derivatives as a new access to cyclobutenes possessing quaternary stereocenters
The Pt(II)- and Pd(II)-catalyzed ring-expansion of alkylidenecyclopropane derivatives leads to the formation of cyclobutenes in good yields. The presence of an enantiomerically pure quaternary stereocenter on the alkylidenecyclopropane gives the corresponding cyclobutenes with the same enantiomeric ratio.
Asymmetric meso-aziridine ring-opening reactions using a chiral zirconium catalyst
We report asymmetric ring-opening reactions of meso-N-benzhydryl aziridines with anilines catalyzed by a Zr-BINOLate complex.
The concise synthesis of chiral
tfb ligands and their application to the rhodium-catalyzed asymmetric arylation of aldehydes
New C2-symmetric tetrafluorobenzobarrelene ligands were prepared and applied successfully to the rhodium-catalyzed asymmetric addition of arylboronic acids to aromatic aldehydes giving chiral diarylmethanols in high yield with high enantioselectivity.
NeoPHOX—an easily accessible P,N-
ligand for iridium-catalyzed asymmetric hydrogenation: preparation, scope and application in the synthesis of demethyl methoxycalamenene
Using a new class of chiral iridium hydrogenation catalysts, the antitumor natural product demethyl calamenene was synthesized in four steps in >20% overall yield and high enantiomeric purity.
Acid-mediated formation of
trifluoromethyl sulfonates from sulfonic acids and a hypervalent iodine trifluoromethylating agent
A new, straightforward synthesis of trifluoromethyl sulfonates, a class of virtually unexplored compounds: another surprising reaction of the hypervalent iodine reagent 1-trifluoromethyl-1,2-benziodoxol-3(1H)-one.
hydrogenation of vinyl boronates
The first Ir-catalyzed asymmetric hydrogenations of vinyl boronates have been performed using low catalyst loadings and pressure (as low as 1 bar). Good selectivities (76–98% ee) were obtained for a range of substrates.
Asymmetric β-boration of α,β-unsaturated
carbonyl compounds promoted by chiral rhodium–bisoxazolinylphenyl catalysts
Enantioselective β-boration of α,β-unsaturated carbonyl compounds with up to 97% ee with bis(pinacolato)diboron was attained with chiral rhodium–bisoxazolinylphenyl acetate complexes.
Direct functionalization of benzylic C–Hs with vinyl acetates via Fe-catalysis
Direct cross-coupling to construct sp3 C–sp3 C bonds via Fe-catalyzed benzylic C–H activation with 1-aryl vinyl acetate is described. The first Heck-type olefination of benzylic C–Hs was also observed with styrene as a reagent.
Barriers to enantiocontrol in Lewis acid catalyzed hetero-Diels–Alder reactions
Lewis bases inhibit the rate of conversion for cycloaddition and those, like aldehydes or nitriles, cause a decrease in enantiocontrol due to the Lewis acidity of the activated complex.
Platinum-catalysed aerobic 1,2-aminooxygenation of alkenes
Platinum(II) salts in combination with copper salts and molecular oxygen catalyse an unprecedented aerobic alkene oxidation that yields cyclic aminooxygenation products under sustainable conditions.
Pronounced effects of substituents on the iridium-catalyzed borylation of
aryl C–H bonds
Iridium trisboryl complexes containing bisphosphine and bipyridine ligands and pinacolate and catecholate substituents are reported.
Total synthesis of
(+)-virgatusinvia AlCl3-catalyzed [3+2] cycloaddition
A stereocontrolled asymmetric synthesis of virgatusin was achieved in five steps from donor–acceptor cyclopropane 1 employing a Lewis acid-catalyzed cyclopropane–aldehyde addition reaction that constructs the tetrahydrofuran.
Direct catalytic asymmetric aldol reaction of
β-keto esters with formaldehyde promoted by a dinuclear Ni2- Schiff base complex
A homodinuclear Ni2-Schiff base-catalyzed direct asymmetric hydroxymethylation of β-keto esters gave products in up to 94% ee with catalyst turnover number (TON) up to 940.
Amino acid salt catalyzed intramolecular Robinson annulation
The silica gel absorbed amino acid salt catalyzed asymmetric intramolecular Robinson annulation reaction has been developed; up to 97% ee was obtained with this readily recoverable organocatalyst.
enantioselective carbenoid insertion into S–H bonds
An asymmetric carbenoid insertion into S–H bonds catalyzed by copper–chiral spiro bisoxazoline complexes has been developed. A series of α-mercaptoesters were produced in high yields with moderate to good enantioselectivities (up to 85% ee). This result represents the best enantioselectivity in the catalytic asymmetric carbenoid S–H bond insertion reaction.
Efficient syntheses of α-pyridones and 3(2H)-isoquinolones through ruthenium-catalyzed cycloisomerization of 3-en-5-ynyl and o-alkynylphenyl nitrones
We report a new catalytic synthesis of α-pyridones and 3(2H)-isoquinolones from readily available 3-en-5-ynyl nitrones and o-alkynylphenyl nitrones; the reaction mechanism is proposed to involve iminyl ketene species through an oxygen transfer process.
Intramolecular cross-coupling of gem-dibromoolefins: a mild approach to 2-bromo benzofused heterocycles
Highly useful 2-halogenated benzofurans and benzothiophenes can be prepared from readily available gem-dibromoolefins using a mild, ligand-free copper catalyzed cross-coupling procedure.
Synthesis of highly enantiomerically enriched planar chiral ruthenium complexes viaPd-catalysed asymmetric hydrogenolysis
Key elements reported are a very efficient microwave synthesis of [RuCp(naphthalene)][PF6], the precursor of [RuCp(CH3CN)3][PF6], and the application of Pd-catalysed asymmetric hydrogenolysis to prochiral ruthenium complexes.
One-step formation of fused tetracyclic skeletons from
cyclohexene-diynes and carbon monoxide through Rh(I)-catalyzed [2 + 2 + 2 + 1] cycloaddition reaction
A novel approach to the rapid construction of 5-7-6-5 fused tetracyclic carbocycles and heterocycles from cyclohexene-diynes and CO in just one step through Rh(I)-catalyzed [2 + 2 + 2 + 1] cycloaddition is described.
amide formation with α′-hydroxyenones as acylating reagents
Amide formation catalyzed by the combination of an N-heterocyclic carbene and 1,2,4-triazole is achieved using α′-hydroxyenones as acylating reagents. No stoichiometric coupling reagents are required.
Phosphabarrelene-modified Rh-catalysts: a new and selective route towards hydroxy-functionalized bicyclic
imidazoles via tandem reactions
8-Hydroxy-6-methyl-5,6,7,8-tetrahydroimidazo[1,2-a]pyridine is formed selectively in high yields by a one-pot tandem hydroformylation–cyclization sequence.
A catalytic synthesis of selectively substituted biaryls through sequential intermolecular coupling involving
arene and ketone C–H bond functionalization
Selectively substituted biaryls containing a ketone unit are obtained under mild conditions in satisfactory yields through sequential intermolecular coupling involving ortho-substituted iodoarenes and ketones in the presence of palladium and norbornene as the only catalysts.
Electronic and steric tuning of chiral
diene ligands for rhodium-catalyzed asymmetric arylation of imines
High efficiency was achieved by the use of an electronically and sterically-modified chiral diene ligand in rhodium-catalyzed asymmetric addition reactions. Asymmetric arylation of imines gave the corresponding diarylmethylamines in high yields with high enantioselectivity in the presence of 0.3 mol% of the diene–rhodium catalyst.
Rhodium catalyzed enantioselective
cyclization of substituted imidazoles via C–H bond activation
The enantioselective intramolecular alkylation of substituted imidazoles with enantiomeric excesses up to 98% has been accomplished by rhodium catalyzed C–H bond functionalization with (S,S′,R,R′)TangPhos as the chiral ligand.
Asymmetric autocatalysis induced by meteoritic
amino acids with hydrogen isotope chirality
Achiral meteoritic glycine and α-methylalanine, with hydrogen isotope (D/H) chirality, acted as the source of chirality in asymmetric autocatalysis with amplification of ee to afford highly enantioenriched 5-pyrimidyl alkanols.
Dynamic kinetic asymmetric transformation in copper catalyzed allylic alkylation
The first dynamic kinetic asymmetric transformation in copper catalyzed allylic alkylation is reported, with enantioselectivities up to 92%.
Nickel/AlMe2Cl-catalysed carbocyanation of
alkynes using arylacetonitriles
Nickel/Lewis acid dual catalysis was found to effect the carbocyanation reaction of alkynes using arylacetonitriles, giving a range of triply substituted acrylonitriles.
Comparative catalytic C–H vs. C–Si activation of
arenes with Pd complexes directed by urea or amide groups
Analysis of regiocontrol in Pd-catalysed C–H activation leads to observations of aryltrimethylsilyl activation and to superior results with urea-based substrates.
Highly asymmetric cobalt-catalyzed aziridination of
alkenes with trichloroethoxysulfonyl azide (TcesN3)
[Co(2,6-DiMeO-ZhuPhyrin)] can aziridinate both aromatic and aliphatic olefins under mild conditions in high yields and excellent enantioselectivities. The catalyst can be conveniently recycled and reused through a precipitation/filtration protocol.
Efficient synthesis of 2,3-dihydro-1H-pyrazoles via a highly selective Pd(0)-catalyzed coupling-cyclization reaction of terminal 2-substituted 2,3-allenyl
hydrazines with aryl iodides
2,3-Dihydro-1H-pyrazoles may be highly selectively synthesized via the Pd(0)-catalyzed coupling-cyclization reaction of 4-non-substituted 2-substituted 2,3-allenyl hydrazines with aryl iodides in moderate to good yields.
Combination of a binaphthol-derived phosphite and a C1-symmetric phosphinamine generates heteroleptic
catalysts in Rh- and Pd-mediated reactions
A heteroleptic catalyst is active in Rh- and Pd-mediated reactions using a 1 : 1 binaphthol-derived phosphite : C1-symmetric phosphinamine ligand combination.
TfOH-catalyzed intramolecular alkyne– ketone metathesis leading to highly substituted five-membered cyclic enones
TfOH-catalyzed intramolecular carbocyclization of tethered alkynyl ketones in MeOH afforded a variety of highly substituted five-membered cyclic enones in good to excellent yields with high selectivities.
Rhodium-catalyzed asymmetric hydroalkoxylation and hydrosulfenylation of diphenylphosphinylallenes
The rhodium-catalyzed intermolecular asymmetric hydroalkoxylation and hydrosulfenylation of diphenylphosphinylallenes gave chiral allylic phosphine oxides substituted with vinyl ether and thioether moieties in high yields with high enantioselectivities.
Efficient copper-catalyzed coupling of aryl chlorides, bromides and iodides with aqueous ammonia
Carbon–nitrogen bond formation with a wide range of aryl halides and aqueous ammonia in the presence of catalytic amounts of cuprous oxide has been achieved. The reaction proceeds in aqueous solution and it eliminates the need for inert atmosphere, expensive catalysts and ligands, anhydrous solvents, and base or other additives.
First iron-catalyzed synthesis of
oximes from styrenes
Aryl-substituted olefins react with t-butyl nitrite and sodium borohydride in the presence of iron(II)phthalocyanine to give oximes in moderate to high yields.
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