Chemoenzymatic synthesis of boron-containing chiral amines and amides

The first application of lipases as catalysts to obtain optically active boron-containing amines and amides is described. We studied several reaction conditions to achieve the kinetic resolution of boron-containing amines via enantioselective acylation mediated by Candida antarctica lipase B (CAL-B). Excellent enantioselectivity (E >200) and high enantiomeric excess (up to >99%) of both the remaining amines and amides were obtained.     

A one-pot synthesis of tertiary amines from amines,lactams and urethanes

A one-pot synthesis of unsymmetrical tertiary amines from amides, lactams and urethanes has been developed. The reaction is general for all cases examined with the exception of N-aryl containing examples, which are not accessible by this method.     

Polymers of tertiary amines

Polymers of tertiary amines and their hydrochlorides of molecular weights in the range 300–2000 have been prepared, starting from trans-1,4-dichlorobutene-2, and primary amines. The polymers present interesting solubility properties. Variation of the reaction conditions leads to crosslinked insoluble polymers. Reaction of the soluble tertiary amine polymers with organic acid dichlorides leads to polymers of tertiary amine–amides, a new type of polymer.     

Preparation of functionalized primary chiral amines and amides via an enantioselective three-component synthesis of propargylamines

A general preparation of functionalized primary chiral amines and amides from propargylamines has been developed. The chirality is established by an enantioselective three-component reaction of an aldehyde, a terminal alkyne and a secondary amine in the presence of copper(I) bromide/Quinap as the catalytic system leading to chiral propargylamines in high yields and enantioselectivities. Functionalization and reduction leads to various primary amines and amides.     

Michael addition of amines and thiols to dehydroalanine amides: a remarkable rate acceleration in water

In water, the rate of Michael addition of amines and thiols to dehydroalanine amides was greatly accelerated, leading to shorter reaction times and higher yields. The scope of the new conditions was tested with a range of amines, thiols, and dehydroalanine amides. The ease and efficiency of this method provides an attractive route to the synthesis of natural and unnatural amino acid derivatives.     

Direct hydrogenation of amides to alcohols and amines under mild conditions

The selective, direct hydrogenation of amides to the corresponding alcohols and amines with cleavage of the C-N bond was discovered. The expected products of C-O cleavage are not formed (except as traces in the case of anilides). The reaction proceeds under mild pressure and neutral, homogeneous conditions using a dearomatized, bipyridyl-based PNN Ru(II) pincer complex as a catalyst. The postulated mechanism involves metal-ligand cooperation by aromatization-dearomatization of the heteroaromatic pincer core and does not involve hydrolytic cleavage of the amide. The simplicity, generality, and efficiency of this environmentally benign process make it attractive for the direct transformations of amides to alcohols and amines in good to excellent yields.     

Acid-free, aminoborane-mediated Ugi-type reaction leading to general utilization of secondary amines

A variety of secondary amines have become utilized in the Ugi reaction by using aminoborane 1 as an iminium ion generator. Aldehydes, secondary amines, and isocyanides are coupled in the presence of 1 at room temperature, giving the corresponding alpha-amino amides in good yields. The nonacidic reaction conditions are beneficial for unique chemoselectivity, where the aldimine functionality is left intact in the present Ugi-type reaction.     

Pivaloylpyruvic acid as a new acylating reagent for amines

Pivaloylpyruvic acid is an efficient reagent for preparative acylation of amines. A method for the synthesis of substituted pivaloylpyruvamides with domination of (Z)-β-keto-enol tautomer is proposed. The structure of pivaloylpyruvic acid and its amides, as well as the specific features of the reaction of pivaloylpyruvic acid with amines, are discussed.     

Reductive hydroxyalkylation/alkylation of amines with lactones/esters

We have developed a one-pot method for the direct intermolecular reductive hydroxyalkylation or alkylation of amines using lactones or esters as the hydroxyalkylating/alkylating reagents. The method is based on the in situ amidation of lactones/esters with DIBAL-H-amine complex (for primary amines) or DIBAL-H-amine hydrochloride salt complex (for secondary amines), followed by reduction of the amides with an excess of DIBAL-H. Different from the reduction of Weinreb amides with DIBAL-H where aldehydes are formed, the reduction of the in situ formed Weinreb amides yielded amines. Moreover, this method is not limited to Weinreb amides, instead, it also works for other amides in general. A plausible mechanism is suggested to account for the outcome of the reactions.     

Neat reaction of carboxylic acid methyl esters and amines for efficient parallel synthesis of scaffold amide libraries

Efficient synthesis of unsubstituted and substituted amides is described. The reaction is characterised by its mildness and ease of work-up. A library of amides, synthesised by heating ester 1 or 2 with various amines has been generated. To cite this article: F. Machetti et al., C. R. Chimie 6 (2003).     

Facile amidation of esters with aromatic amines promoted by lanthanide tris (amide) complexes

The development of catalysts capable of catalyzing amidation of esters with amines to construct amides under mild conditions is of great importance. Compared to aliphatic amines, the direct catalytic amidation of esters with less nucleophilic aromatic amines is rather difficult. Employing simple lanthanide tris (amide) complexes Ln[N (SiMe₃)₂]₃(μ-Cl)Li (THF)₃ as the catalysts, it was found a broad range of aromatic amines and esters were efficiently converted into various amides in good yields under mild conditions. A plausible mechanism for this transformation was experimentally supported as starting from an amide exchange reaction between the lanthanide tris (amide) complex and the substrate amine.     

An efficient method to convert lactams and amides into 2,2-dialkylated amines

A practical method for the synthesis of gem-2,2-disubstituted tertiary amines from the corresponding lactams (or amides) is reported. It is based on the reaction of thioiminium ions, easily prepared from lactams and amides with organometallic reagents such allylmagnesium, benzylmagnesium, and primary alkylcerium reagents.     

Fast synthesis of uronamides by non-catalyzed opening of glucopyranurono-6,1-lactone with amines, amino acids, and aminosugars

A series of glucuronamides have been easily prepared by reaction of glucopyranurono-6,1-lactone with a wide variety of amines. Primary and secondary amines gave the corresponding amides in short times, high yields. Diamines led to diuronamide compounds, whereas glucuronic acid conjugates were obtained with amino acids. The reaction with aminosugars afforded disaccharide analogues. In all products, the anomeric position is free for further conversion.     

Heteroacyl azides as acylating agents for aromatic or heteroaromatic amines

The possibility of formation of substituted heterocyclic amides from heteroacyl azides and aromatic or heteroaromatic amines was investigated. Although acylation proceeded in some cases under mild reaction conditions, formation of N,N′-disubstituted ureas was the main process at elevated temperatures.     

Selective mono- and di-N-alkylation of aromatic amines with alcohols and acylation of aromatic amines using Ph3P/DDQ

Selective N-monoalkylation of aromatic amines with 1° and 2° alcohols and conversion of aromatic amines to amides are performed immediately and in excellent yields using triphenylphosphine (PPh₃) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in dichloromethane at room temperature. Symmetrical and unsymmetrical N,N-dialkylation of aromatic amines are also carried out in modest yield at room temperature by this reagent system.     

The ruthenium-catalyzed reduction and reductive N-alkylation of secondary amides with hydrosilanes: practical synthesis of secondary and tertiary amines by judicious choice of hydrosilanes

A triruthenium cluster, (mu3,eta2,eta3,eta5-acenaphthylene)Ru3(CO)7 (1) catalyzes the reaction of secondary amides with hydrosilanes, yielding a mixture of secondary amines, tertiary amines, and silyl enamines. Production of secondary amines with complete selectivity is achieved by the use of higher concentration of the catalyst (3 mol %) and the use of bifunctional hydrosilanes such as 1,1,3,3-tetramethyldisiloxane. Acidic workup of the reaction mixture affords the corresponding ammonium salts, which can be treated with a base, providing a facile method for isolation of secondary amines with high purity. In contrast, tertiary amines are formed with high selectivity by using lower concentration of the catalyst (1 mol %) and polymeric hydrosiloxanes (PMHS) as reducing agent. Reduction with PMHS encapsulates the ruthenium catalyst and organic byproducts to the insoluble silicone resin. The two reaction manifolds are applicable to various secondary amides and are practical in that the procedures provide the desired secondary or tertiary amine as a single product. The product contaminated with only minimal amounts of ruthenium and silicon residues. On the basis of the products and observed side products as well as NMR studies a mechanistic scenario for the reaction is also described.     

Regio- and stereoselective methods of synthesis of higher unsaturated sulfides and amines with participation of metal complex catalysts

Regio- and stereoselective methods of synthesis of octadienyl sulfides and amines that are based on the reaction of mercaptides and amides of aluminum with allyl electrophiles catalyzed by complexes of Pd and Zr have been developed.Translated from Ivestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 649–655, March, 1991.     

Reaction of α,α-dimethyl-γ-(1-phe nyl-3-methyl-4-pyrazolyl)- β , γ-butenolide with primary amines and ammonia

The conditions for the formation of amides of 4-keto acids, 2-oxo-5-hydroxypyrrolidlnes, 2-oxo-2,3-dihydropyrroles, or 2-oxo-5-aminotetrahydrofurans by reaction of a Δβ,γ-butenolide with primary amines were determined. The reaction with primary aliphatic amines — benzylamine and methylamine — in ethanol gives 2-oxo-5-hydroxypyrrolidines, while reaction with benzylamine in benzene gives the amide of a 4-keto acid. 2-Oxo-5-anilinotetrahydrofuran is formed in the reaction with aniline.     

A novel synthesis of tocopheryl amines and amides

We report the synthesis of tocopheryl amines and amides from commercially available tocopherols. This synthesis improves the yield and diastereomeric purity of these biologically important compounds. The tocopheryl amines were prepared from the corresponding α- and δ-tocopherols using two distinct synthetic routes. The introduction of the C(6)-amino group can be achieved by aryl nitration/reduction or by Pd-catalyzed substitution of an aryl triflate, depending on the structure of the starting material. We also prepared the succinamide and maleamide derivatives of each amine. Tocopheryl amides are more potent pro-apoptotic anti-cancer agents than the corresponding α-tocopheryl esters. These compounds act selectively within the mitochondria of cancer cells.     

Pd-catalyzed carbonyl insertion coupling reactions of a hypervalent iodoheterocycle with alcohols and amines

The palladium-catalyzed cross-coupling carbonyl insertion reaction between 3,7-bis(N,N-dimethylamino)-10H-dibenz[b,e]iodinium iodide (1) and alcohols or amines 2 is described. Some new amides and esters 3 containing an active iodo functional group have been prepared in 65-91% yields.