Use of functionalized aromatic organozinc reagents in the three-component Mannich-type synthesis of diarylmethylamines

Efficient syntheses of functionalized diarylmethylamines have been realized according to a one-step three-component coupling between an aromatic aldehyde, a secondary amine and an aromatic organozinc reagent. Phenyl rings can be substituted by functional groups and either aromatic or non-aromatic amines can be used in this process.     

Nickel(II)-catalyzed carbon-carbon bond formation reaction of functionalized organozinc reagents with aromatic aldehydes

In the presence of a silylating reagent and catalytic amount of Ni(acac)₂, organozinc halides reacted with aromatic aldehydes to give the corresponding dialkylation products in good to excellent yields under mild conditions.     

Straightforward three-component synthesis of diarylmethylpiperazines and 1,2-diarylethylpiperazines

Several functionalized diarylmethylpiperazines and 1,2-diarylethylpiperazines have been synthesized in moderate to high yield according to a one-step three-component coupling between an aromatic or a benzylic organozinc reagent, a piperazine derivative, and an aromatic aldehyde. The procedure can be extended to the synthesis of benzylpiperazine derivatives or β-arylethylpiperazines toward the use of paraformaldehyde or aliphatic aldehydes.     

New progress in the cobalt-catalysed synthesis of aromatic organozinc compounds by reduction of aromatic halides by zinc dust

The experimental conditions of the cobalt-catalysed synthesis of aromatic organozinc species from the corresponding bromides have been optimised. The preparation of numerous aromatic organozinc reagents under these optimised conditions is reported, with yields between 67 and 99%.     

Convenient processes for the synthesis of aromatic ketones from aryl bromides and carboxylic anhydrides using a cobalt catalysis

The cross-coupling of various para- and meta-substituted aromatic bromides, mostly bearing sensitive moieties, with several carboxylic acid anhydrides is reported. This reaction can be carried out in two steps, by forming an aromatic organozinc reagent via cobalt catalysis in the first step, or even more interestingly in a single step, also by using a cobalt-based catalyst. The aromatic ketones are obtained by these new, mild, and convenient methods in 30-79% yields versus starting aryl bromide. Results are also disclosed that suggest the role played by cobalt species in the coupling of organozinc reagents with electrophiles could be similar to those of more commonplace transition metal complexes.     

Selective debenzylation of aromatic benzyl ethers by silica-supported sodium hydrogen sulfate

A new debenzylation of aromatic benzyl ethers by silica-supported sodium hydrogen sulfate is described. The process proceeds selectively and efficiently in good to excellent yields without affecting sensitive functional groups such as nitro, COOMe, aldehyde, ketone, and tosyl.     

DNA-based aromatic zipper fastened by an aromatic stacking interaction

A novel thymidine-methyl red conjugate was synthesized and incorporated into oligodeoxyribonucleotides (ODNs). The ODNs containing the conjugate formed a novel nucleic acid-based structural motif, the aromatic zipper, which fastens via the stacking interactions of aromatic residues that are attached to DNA strands. The aromatic zipper can be used to stabilize structural motifs in nucleic acids and their analogues, such as hairpin structures, by fastening their ends.     

Addition of benzylic and allylic organozinc and Grignard reagents to resin-bound imines to provide alpha-branched secondary amines bearing a wide variety of functional groups. Utility in the synthesis of beta-3 adrenergic receptor agonists

Benzylic and allylic organozinc and Grignard reagents have been added to resin-bound imines to provide alpha-branched secondary amines. Many functional groups, including electrophilic groups, were compatible with this methodology. Three modules--a resin-bound primary amine, an aromatic aldehyde, and the organometallic--were independently varied to produce a combinatorial library of alpha-branched secondary amines designed as beta-3 adrenergic receptor agonists.     

Spectrophotometric determination and kinetic studies of condensation of aromatic aldehydes with 1,3-dimethylbarbituric acid

The condensation reaction of 1,3-dimethylbarbituric acid with aromatic aldehydes in ethanol has been investigated spectrophotometrically at 25–35°C. The reaction follows overall second-order kinetics, first-order each in reactant. From the dependence of the rate constants on temperature, activation parameters have been calculated. The rate of condensation increases with the presence of electron donating groups on the aromatic ring of the aldehyde. The rate-determining step involves dehydration of the aldol intermediate. The reaction was found to be catalyzed by HCl solutions. Based on this reaction, determination of 10 aromatic aldehydes in a concentration range of 0.13–70.25 μg/ml is proposed. The method was applied for determination of barbituric and 1,3-dimethylbarbituric acids also.     

Pentamethylcyclopentadienide in organic synthesis: nucleophilic addition of lithium pentamethylcyclopentadienide to aromatic aldehydes and carbon-carbon bond cleavage of the adducts affording the parent aldehydes

Treatment of aromatic aldehyde with lithium pentamethylcyclopentadienide provided the corresponding carbinol in excellent yield. The carbinol returns to the parent aldehyde and pentamethylcyclopentadiene upon exposure to an acid or due to heating. The combination of the two reactions can represent a protection of aromatic aldehyde.     

One-pot synthesis of N-aryl propargylamine from aromatic boronic acid,aqueous ammonia,and propargyl bromide under microwave-assisted conditions

A facile,one-pot synthesis of N-aryl propargylamine from aromatic boronic acid,aqueous ammonia,and propargyl bromide has been achieved under microwave-assisted conditions.The reactions can be smoothly completed within a total 10 min through a two-step procedure,including copper-catalyzed coupling of aromatic boronic acids with aqueous ammonia and following propargylation by propargyl bromide.     

Nucleus-fluorinated aromatic polyethers

Methods of synthesis, the structure, properties, and application areas of nucleus-fluorinated aromatic polyethers are considered. The main attention is given to polymers for which chain propagation occurs via formation of an ether bond, and the fluorinated monomers suitable for the synthesis of these polymers are indicated. Approaches to the incorporation of sulfonic acid, phosphoric acid, aldehyde, and maleimide groups and other reactive moieties into fluorinated aromatic polyethers are analyzed.     

DFT study of “all-metal” aromatic compounds

An overview of recent quantum chemical studies on all-metal aromatic compounds is presented. Novel classes of inorganic molecules containing bonds that are characterized by a common ring-shaped electron density are reviewed. The mechanistic insight gained for the aromatic character of all-metal aromatic molecules is discussed and the predictive nature of the electronic structure calculation methods particularly those based on density functional theory (DFT) is highlighted. The indicators of aromaticity (aromaticity criteria) - structural, magnetic, energetic and reactivity-based measures - many of which are accessible through quantum chemical calculations are also outlined herein.     

One-step synthesis of polysubstituted benzene derivatives by multi-component cyclization of alpha-bromoacetate, malononitrile and aromatic aldehydes

Polysubstituted benzene derivatives with an unprecedented substitution pattern are produced in a novel one-pot multi-component cyclization reaction from pyridine, ethyl alpha-bromoacetate, malononitrile and aromatic aldehyde in refluxing acetonitrile.     

Tandem synthesis of aromatic amides from styrenes in water

An expedient one-pot synthesis of aromatic amides has been reported from styrenes in the presence of N-bromosuccinimide and iodine by using aqueous ammonia in water. The reaction proceeds through the formation of α-bromoketone as an intermediate in the presence of NBS and water. α-Bromoketone on reaction with iodine forms bromodiiodoketone which on nucleophilic substitution with aqueous ammonia gives aromatic amide. Substituted aromatic amides were obtained in good yields with wide functional group compatibility.     

Highly diastereoselective formation of 3,7-dioxabicyclo[3.3.0]octan-2-ones in reaction of 2-arylcyclopropanedicarboxylates with aromatic aldehydes using 1,2-zwitterionic reactivity type

A new reaction of 2-arylcyclopropane-1,1-dicarboxylates (ACDC) with aromatic aldehydes that occurs via generation of a 1,2-zwitterionic intermediate in the presence of GaCl₃ has been developed. This process results in the 3,7-dioxabicyclo[3.3.0]octane frame by addition of two aldehyde molecules to an ACDC molecule. The reaction is a complex anionic-cationic cascade process involving the formation of two C–C bonds, two C–O bonds, and five stereocenters. The process occurs with high diastereoselectivity to give only one diastereomer. A probable reaction mechanism is suggested and confirmed by NMR monitoring data.     

Original formation of benzyl benzoates by TDAE strategy

We report herein an original photoinduced electron transfer reaction between an aromatic aldehyde and TDAE in the presence of chloromethyl-dimethoxybenzenes. Thus, the reaction of 1-chloromethyl-2,5-dimethoxy-3,4,6-trimethylbenzene (1), dichlorides 4 and 5 with a series of aromatic aldehydes, in the presence of TDAE and under light catalysis, gave the corresponding benzyl benzoates.     

Synthesis of 2,6—（substituded）pyridine Derivatives Using Amide and Imine Groups

A new ‘two-armed’ acyclic diamide Ia 2,6-bis(1-ethanecarbozamido-2-amino)pyridine,and a new series of aromatic aldehyde schiff bases containing pyridine ring and arnide bridge,ILa-f, were prepared.The compounds were characterized by elemental analysis,IR,^1HNMR and MS.The bioactivity half inhibitory concentration C1/2 is given.     

CuCl-catalyzed aerobic oxidative reaction of primary aromatic amines

The oxidations of primary aromatic amines were investigated. Cuprous chloride-air system can catalyze the oxidation of primary aromatic amines to azo derivatives, anils, and/or quinone anils. The experimental procedure is simple and the products could be easily isolated in high yields.     

The occurrence of electron transfer in aromatic nitration: dynamical aspects

Electron transfer (ET) from toluene to the nitronium ion in the region of van der Waals intermolecular distances has been investigated by a quantum dynamical analysis performed on potential-energy surfaces computed at the ab initio multireference configuration interaction level. The results show that ET is very fast, occurring on a timescale of a few picoseconds. This has important implications for the mechanism of aromatic nitration: the ET path can compete efficiently with the direct attack of the nitronium ion to the aromatic substrate to yield the Wheland intermediate and that could explain some unsettled points in the mechanism of aromatic nitration. Received: 16 September 1999 / Accepted: 3 February 2000 / Published online: 12 May 2000