Ir-catalyzed asymmetric allylic alkylation using chiral diaminophosphine oxides: DIAPHOXs. Formal enantioselective synthesis of (−)-paroxetine

An Ir-catalyzed asymmetric allylic alkylation using chiral diaminophosphine oxide is described. Asymmetric allylic alkylation of terminal allylic carbonates proceeded using 5 mol % of Ir catalyst, 5 mol % of DIAPHOX 1i, 10 mol % of NaPF₆, 10 mol % of LiOAc, and N,O-bis(trimethylsilyl)acetamide (BSA), affording the corresponding branched products in excellent yield and in up to 95% ee. The developed catalytic asymmetric reaction was successfully applied to a formal enantioselective synthesis of (−)-paroxetine.     

Ir-catalyzed asymmetric allylic amination using chiral diaminophosphine oxides

An Ir-catalyzed asymmetric allylic amination using chiral diaminophosphine oxide is described. Asymmetric allylic amination of terminal allylic carbonates proceeded in the presence of 2 mol % of Ir catalyst, 2 mol % of chiral diaminophosphine oxide, 5 mol % of NaPF₆, and BSA, affording the chiral branched allylic amines in up to 95% ee.     

Iridium-catalyzed oxidative esterification reaction of aliphatic aldehydes and olefinic alcohols with precoordination of the double bond of alcohols to iridium

A novel iridium-catalyzed oxidative esterification reaction of aliphatic aldehydes and olefinic alcohols in toluene was found under mild conditions of [IrCl(cod)]₂ (5 mol %) in combination with K₂CO₃ (10 mol %) at rt.     

Copper mediated atom transfer radical cyclisations with AIBN

We have shown that it is possible to mediate a range of 5-exo trig and 5-exo dig atom transfer radical cyclisations of bromoacetamides using 0.1-1 mol % CuBr or CuBr₂ in conjunction with 0.1-1 mol % tri(pyridin-2-ylmethyl)amine and 10 mol % AIBN. This equates to a 30-300-fold reduction in the amount of catalyst previously reported for these reactions and allows cyclisation to be carried out with the more oxidatively stable CuBr₂ without the requirement of an inert atmosphere.     

Amino acid-mediated Goldberg reactions between amides and aryl iodides

A highly general, experimentally simple, and inexpensive catalyst system was developed for the amidation of aryl iodides by using 5 mol % of CuI as catalyst, 20 mol % of an amino acid as ligand, and K₃PO₄ as base.     

Efficient and selective alkylation of arenes and heteroarenes with benzyl and allyl ethers using a Ir/Sn bimetallic catalyst

A high-valent heterobimetallic catalyst namely [Ir₂(COD)₂(SnCl₃)₂(Cl)₂(μ-Cl)₂] (5 mol %), or dual catalyst system of [Ir(COD)Cl]₂ (1 mol %) and SnCl₄ (4 mol %), promotes the benzylation or allylation of arenes and heteroarenes using ethers as the alkylating agents. An electrophilic mechanism is proposed from a Hammett correlation.     

One-pot synthesis of 1,4-diarylsubstituted 1,3-diynes from the sequential coupling reactions of aryl iodides and propiolic acid

1,4-Disubstituted 1,3-dialkynes were obtained from the one-pot palladium/copper-catalyzed coupling reactions of aryl iodide and propiolic acid. The optimized catalytic system consisted of 5.0 mol % Pd(PPh₃)₂Cl₂, 10 mol % dppb, 10 mol % CuI, 2.4 equiv of DBU, and 1.2 equiv of K₂CO₃. The coupling reaction was carried out at 30 °C for 6 h and subsequently at 80 °C for 3 h.     

Rapid access to homoallylic alcohols via Pd(OAc)2 catalyzed Barbier type allylation in presence of DMAP

DMAP was found to accelerate significantly the rate of Pd(OAc)₂ catalyzed Barbier type allylation of carbonyl compounds by allylbromide using SnCl₂·2H₂O as reducing agent. Both aldehyde as well as ketones produced excellent yields within a short reaction time in the presence of 3 mol % of Pd(OAc)₂ and 12 mol % of DMAP at room temperature. Aldehydes could be allylated within 5–10 min whereas, in case of ketones, the reaction completes in 45–120 min.     

Preparation of 2,2-difluoro-1-trialkylsilylethenylstannanes and their cross-coupling reactions

Reaction of 2 with bis(tributyltin) in the presence of 3 mol % Pd₂(dba)₃, 6 mol % XPhos, and 30 equiv of LiBr in wet and air bubbled THF at reflux for 8 h afforded the desired products 3 in 73–74% yields. The cross-coupling reaction of 3a with aryl iodides in the presence of 10 mol % Pd(PPh₃)₄ and 10 mol % CuI afforded the coupled products 4a–p in 47–90% yields. The coupling reaction of 3b with various alkynyl bromides having aryl-, alkyl, or trialkylsilyl group also afforded the corresponding 1,3-enynes 5a–g in 61–77% yields.     

Gold(I)-catalyzed benzannulation of 3-hydroxy-1,5-enynes: an efficient synthesis of substituted tetrahydronaphthalenes and related compounds

We report a novel gold(I)-catalyzed benzannulation of 3-hydroxy-1,5-enynes to prepare tetrahydronaphthalenes. The reaction is catalyzed by 2.5 mol % Ph₃PAuCl and 2.5 mol % AgOTf in dichloromethane. We discovered that this process can be also catalyzed by 1 mol % Ph₃PAuCl and 1 mol % TfOH. To the best of our knowledge, this constitutes the first report of an active gold catalyst generated from Au(PPh₃)Cl and triflic acid. This mild process is compatible with a variety of functional groups and proves to be an effective method to synthesize various meta-substituted aromatic rings in good yields.     

Highly enantioselective addition of linear alkyl alkynes to linear aldehydes

It is discovered that the use of biscyclohexylamine (Cy₂NH) as an additive can greatly enhance the enantioselectivity for the reaction of linear alkyl alkynes with linear aldehydes. The combination of (S)-BINOL (20 mol %), Cy₂NH (5 mol %), ZnEt₂ (2 equiv), and Ti(OⁱPr)₄ (0.5 equiv) catalyzes the reaction at room temperature in diethyl ether solution with 81-89% ee and 57-77% yield.     

Iridium-catalyzed double incorporation reaction of N-benzylmaleimide to styrene via ortho-C-H bond activation, initiated by precoordination of the double bond of styrene to iridium

Reaction of styrene with N-benzylmaleimide in the presence of [IrCl(cod)]₂ (5 mol %) and bpy (10 mol %) in an autoclave (1 MPa of Ar) at 150 °C for 18 h stereoselectively led to the formation of a new cyclic product. The structure of the product suggests that a novel iridium-catalyzed double incorporation reaction takes place via a metallacyclopentane formed after ortho-C-H activation.     

Catalytic addition of alkenylzirconocene chloride to 3,4-dihydroisoquinoline and its enantioselective reaction

The addition of alkenylzirconocene chloride to 3,4-dihydroisoquinoline in the presence of a stoichiometric amount of acylating agent such as (Boc)₂O or ClCOOC₂H₅ was carried out in the presence of a catalytic amount of Cu(I) (10 mol %) to give an alkenylation-carbamation product. The enantioselective addition (56-75%ee) of the alkenylzirconocene chloride was also achieved under Cu(I)/chiral amine (10 mol %) conditions.     

Au(I)/Ag(I)-catalyzed annulation of sugar aldehyde tethered with 3-phenylprop-2-yn-1-yl ether with aryl amines for the pyrano[4,3-b]quinoline derivatives

Aryl amines undergo smooth annulation with O-phenylpropynyl sugar aldehyde in the presence of the Ph₃PAuCl (10 mol %)/AgSbF₆ (10 mol %) catalytic system to afford the corresponding tetrahydro-3aH-spiro[[1,3]dioxolo[4″,5″:4′,5′]furo[3′,2′:5,6]pyrano[4,3-b]quinoline-2,1′-cyclohexane] derivatives in good yields and selectivity.     

An efficient and simple Morita-Baylis-Hillman reaction based on the N-methylpyrrolidine-Ba(OH)2 catalytic system

By using of precise catalytic amount of N-methylpyrrolidine (5 mol %) and Ba(OH)₂ (1.5 mol %) in H₂O/CH₃OH 5/1 or CH₃OH/CH₂Cl₂ 3/1 solvent mixtures at T=0 °C a Morita-Baylis-Hillman derivatives could be obtained in good to excellent yield from 2-cyclopenten-1-one, 2-cyclohexen-1-one and formaldehyde and diverse aryl aldehydes after suitable reaction time.     

Synthesis of 1,2-dihydroisoquinolines via the reaction of ortho-alkynylarylimines with bis-π-allylpalladium

The reaction of the ortho-alkynylarylimines 1 with allyltributylstannane and allyl chloride in the presence of allylpalladium chloride dimer (5 mol %) and Cu(OAc)₂ (20 mol %) in CH₃CN at 50 °C gave the 1,4-diallyl-1,2-dihydroisoquinolines 2 in good yields. Most probably, the reaction proceeds through tandem bis-allylation of the imine-alkyne functional groups with bis-π-allylpalladium.     

Pyridinium chlorochromate catalyzed oxidation of alcohols to aldehydes and ketones with periodic acid

A facile pyridinium chlorochromate (PCC) catalyzed (2 mol %) oxidation of alcohols to ketones and aldehydes using 1.05 equiv of H₅IO₆ in acetonitrile is described here.     

Catalytic-adsorptive stripping voltammetric determination of ultra-trace iridium(III). Application to fresh- and sea-water

An extremely sensitive stripping voltammetric procedure for ultra-trace determination of iridium(III) is reported. The method is based on the interfacial accumulation of the iridium(III)-CTAB complex onto the glassy carbon electrode, followed by the catalytic reduction of the adsorbed complex in the presence of bromate. 0.3 mol L⁻¹ acetate buffer pH 4.7 + 6.9 × 10⁻² mol L⁻¹ NaBrO₃ + 2.7 × 10⁻⁵ mol L⁻¹ cetyltrimethylammonium bromide (CTAB) + 0.2 mol L⁻¹ KCl was employed as the supporting electrolyte.The analytical procedure was verified by the analysis of the standard reference materials: Sea Water BCR-CRM 403 and Fresh Water NIST-SRM 1643d.The accuracy, expressed as relative error e%, was satisfactory, being lower than 6%, while precision as repeatability, expressed as relative standard deviation s_r%, was generally lower than 5%. The limit of detection was of the order of 2-3 ng L⁻¹.Once set up on the standard reference materials, the analytical procedure was transferred and applied to superficial water sampled in proximity to superhighway and in the Po river mouth area.     

Copper-catalyzed cross-coupling of sulfonamides with aryl iodides and bromides facilitated by amino acid ligands

A highly general, convenient, and inexpensive catalyst system was developed for the N-arylation of sulfonamides with aryl iodides or bromides by using 5-20 mol % of CuI as catalyst, 20 mol % of N-methylglycine (for aryl iodides) or N,N-dimethylglycine (for aryl bromides) as ligand, and K₃PO₄ as base.     

Pd(OAc)2-catalyzed C-H activation of indoles: a facile synthesis of 3-cyanoindoles

Indoles undergo smooth cyanation with CuCN in the presence of 20 mol % Pd(OAc)₂ and 40 mol % CuBr₂ in DMF to produce a wide range of the corresponding 3-cyanoindoles in good yields with high regioselectivity.