Zn-promoted regioselective and sequence-selective one-pot joining reaction of three components: alkyl iodides, alpha,beta-unsaturated esters (or nitriles), and acylating agents

One-pot treatment of alkyl iodides, alpha,beta-unsaturated esters (or nitriles), and acylating agents such as nitriles or acid anhydrides in the presence of Zn metal at room temperature in the same reaction system brought about a regioselective and sequence-selective three-component joining reaction involving first C-alkylation at the beta-position and second C-acylation at the alpha-position of alpha,beta-unsaturated esters (or nitriles) to afford the corresponding alpha,alpha-dialkylketoesters (or alpha,alpha-dialkylketonitriles) in moderate to good yields. [reaction: see text]     

Synthesis of alkyl iodides/nitriles from carbonyl compounds using novel ruthenium tris(2,2,6,6-tetramethyl-3,5-heptanedionate) as catalyst

Aldehydes and ketones were hydrogenated to the corresponding alcohols, which were then transformed in situ into their respective iodides and nitriles in good yields. A structurally well-defined O-containing transition metal complex, Ru (TMHD)₃, was found to be the active catalyst for hydrogenation, iodination and cyanation reactions. It has high affinity for the transformation of benzylic alcohols to iodides and nitriles.     

Silicaphosphine (Silphos): a filterable reagent for the conversion of alcohols and thiols to alkyl bromides and iodides

Silicaphosphine (Silphos), [P(Cl)_3−n(SiO₂)_n], as a new heterogeneous reagent is introduced. This reagent converts alcohols and thiols to their corresponding bromides and iodides in the presence of X₂ (X=Br, I) in refluxing CH₃CN in high to quantitative yields. Use of Silphos provides a highly practical method for the easy separation of the Silphos oxide byproduct by a simple filtration.     

An efficient and facile one-pot synthesis of cyanohydrin esters from carbonyl compounds catalyzed by iron(III) chloride

A variety of cyanohydrin esters were readily prepared from carbonyl compounds with trimethylsilyl cyanide and acid anhydride under the influence of a catalytic amount of iron(III) chloride in a convenient one-pot procedure.     

Iron(III) triflate-catalyzed one-pot synthesis of acetal-type protected cyanohydrins from carbonyl compounds

A variety of cyanohydrin THP ethers were readily prepared from carbonyl compounds with trimethylsilyl cyanide and tetrahydropyran-2-yl acetate under the influence of a catalytic amount of iron(III) triflate in a convenient one-pot procedure. This method was also effective to prepare O-protected cyanohydrins by various acetal-type protective groups.     

NbCl5-Catalyzed one-pot Mannich-type reaction: three component synthesis of β-amino carbonyl compounds

Three-component Mannich-type reaction of acetophenone, aromatic aldehydes and aromatic amines was catalyzed by NbCl₅ at ambient temperature to give various β-amino ketones in high yields.     

Observations on the copper(II) catalyzed reactions of enaminones and dimethyl diazomalonate

The Cu(acac)₂ catalyzed reactions of dimethyl diazomalonate with enaminones yielded 1,5-cyclization and α-CH insertion products. In the case of anilino derivatives (R¹ or R² = Ph), products resulting from an unusual insertion to the benzoyl ring dominated the reaction.     

Dual reactivity of imidic carbonyl ylides in Rh(II)-catalyzed reactions of α-diazocarbonyl compounds with succinimide

Stabilization of imidic carbonyl ylides derived from α-diazocarbonyl compounds and succinimide occurs in two different ways: ylides from diazoesters experience a [1,4]-hydrogen shift to produce the corresponding O-alkylimidates while their analogues with at least one acyl group undergo [1,5]-electrocyclization yielding 1,3-dioxoles.     

Facile protection of carbonyl compounds as oxathiolanes and transoxathioacetalization of oxyacetals promoted by iron(III) trifluoroacetate or trifluoromethanesulfonate as chemoselective and recyclable catalysts

Oxathioacetalization of carbonyl compounds and transoxathioacetalization of O,O-acetals/ketals are reported under nearly neutral conditions promoted by iron(III) trifluoroacetate [Fe(CF₃CO₂)₃] or trifluoromethanesulfonate [Fe(CF₃SO₃)₃] as recyclable and highly efficient Lewis acid catalysts.     

Direct synthesis of tetrahydropyrans via one-pot Babier-Prins cyclization of allylbromide with carbonyl compounds promoted by RTILs BPyX/SnX′2 or BBIMBr/SnBr2

Tetrahydropyran compounds can be directly synthesized from allylbromide and carbonyl compounds by means of one-pot Babier-Prins cyclization promoted by BPyX/SnX′₂ or BBIMBr/SnBr₂ complex (functionalized RTILs) under solvent-free conditions. 2,6-Homo-bissubstituted- and 2,6,6-trisubstituted, especially 6-(spirocycloalkyl)-, tetrahydropyran compounds can be prepared in good yields.     

2,4,6-Trichloro[1,3,5]triazine (TCT)-catalyzed one-pot Mannich-type reaction: three component synthesis of β-amino carbonyl compounds

Abstract

Three-component Mannich-type reaction of acetophenon, aromatic aldehydes, and aromatic amines is catalyzed by 2,4,6-trichloro[1,3,5]triazine at ambient temperature in EtOH and solvent-free conditions to give various β-amino ketones in high yields.     

Preyssler-type heteropoly acid:A new,mild and efficient catalyst for protection of carbonyl compounds

Preyssler-type heteropoly acid is introduced as a new,mild and efficient catalyst for protection of a variety of carbonyl compounds with 1,3-propane dithiol.     

Reduction and coupling reaction of carbonyl compounds by KI/Fe(OH)3 in aqueous media

ABSTRACT

A small amount of ferric hydroxide was found to catalyze KI-activated coupling of aromatic aldehydes and acetophenone to give the corresponding pinacols in high yields. The ratio of meso to dl isomer was approximately 1:1. Most aliphatic aldehydes and ketones were unreactive under the same conditions.     

N-Acetyl-N,N-dipyrid-2-yl (cyclooctadiene) rhodium (I) and iridium (I) complexes: Synthesis, X-ray structures, their use in hydroformylation and carbonyl hydrosilylation reactions and in the polymerization of diazocompounds

The synthesis of novel N-acetyl-N,N-dipyrid-2-yl complexes of Rh^I and Ir^I, i.e. [RhCl(CH₃CONPy₂)(COD)] (1) and [IrCl(CH₃CONPy₂)(COD)] (2), respectively, is described. Upon prolonged treatment in CH₂Cl₂ at room temperature, complex 1 is transformed into a cationic Rh-complex, i.e. [Rh(CH₃CONPy₂)(COD)⁺RhCl₂(COD)⁻] (1a). Compound 1a crystallizes in the monoclinic space group P2₁/c, complex 2 crystallizes in the triclinic space group . Compound 1 was investigated for its catalytic activity in the hydroformylation of cyclooctene as well as of 1-octene. In addition, 1 was used in various carbonyl hydrosilylation reactions of both aldehydes and ketones. There, turn-over numbers up to 50 000 and yields in the range of 85-100% were observed. Finally, compound 1 was successfully used for the polymerization of N₂CHCOOEt yielding highly stereoregular poly(ethoxycarbonylcarbene) with M_w = 67 000 g/mol and a polydispersity index (PDI) of 2.59.     

[Hmim]_3PW_(12)O_(40):A high-efficient and green catalyst for the acetalization of carbonyl compounds

<正>[Hmim]_3PW_(12)O_(40) was developed and used in the acetalization of carbonyl compounds in excellent yields.The ionic liquidheteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separation system with the ease of product as well as catalyst separation.The catalyst was recycled more than 10 times without any apparent loss of catalytic activity.     

A convenient one-pot approach to Paclitaxel (Taxol) side chain via 1,3-dipolar cycloaddition of carbonyl ylides and N-benzoylbenzyl imines

An efficient cascade approach to α-hydroxy-β-amino acid derivatives is reported, which goes through a 1,3-dipolar cycloaddition of carbonyl ylides and N-benzoylbenzyl imines and followed by hydrolysis under acidic conditions. This is the first example of using N-benzoylbenzyl imine as dipolarophile for 1,3-dipolar cycloaddition with carbonyl ylide, which provides a direct and convenient access for the one-pot synthesis of paclitaxel side chain and its derivatives.     

Rh(1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene)(COD) tetrafluoroborate, an unsymmetrical Rh-homoazallylcarbene: synthesis, X-ray structure and reactivity in carbonyl arylation and hydrosilylation reactions

The synthesis of novel Rh(1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene)(COD) tetrafluoroborate (1, COD = η⁴-1,5-cyclooctadiene) is described. The N-heterocyclic carbene acts as a bidentate ligand with the carbene coordinating to the Rh(I) center and an arene group acting as a homoazallyl ligand. 1 was used in various carbonyl arylation and hydrosilylation reactions allowing the formation of the desired products with unprecedented selectivity and efficiency. Thus, turn-over numbers (TONs) up to 2000 were achieved.     

Synthesis, characterization and structure of a tetrameric DABCO-bromine complex: a novel oxidizing agent for oxidation of alcohols to carbonyl compounds

A tetrameric DABCO-bromine complex was synthesized, characterized and utilized as a novel active bromine complex for the oxidation of alcohols to carbonyl compounds.     

Titanocene(II)-promoted, one-pot, three-component coupling of thioacetals, alkynyl sulfones, and carbonyl compounds: highly stereoselective formation of tert-homopropargyl alcohols

Titanocene alkylidene complexes, generated by desulfurizative titanation of thioacetals with Cp2Ti[P(OEt)3]2, reacted with alkynyl methyl sulfones to produce organotitanium species, which gave tert-homopropargyl alcohols with high diastereoselectivity on treatment with aromatic and alpha,beta-unsaturated ketones.