A convenient synthesis of (E)-α-alkylidene-γ-lactams and (E)-3-alkylideneoxindoles by rhodium-catalyzed intramolecular hydroamidation

Rhodium-catalyzed carbonylative cyclization without carbon monoxide was investigated. Cyclization of various formamides having alkynyl groups proceeded smoothly in the presence of Rh₄(CO)₁₂ to provide α-alkylidene-γ-lactams or 3-alkylideneoxindoles in moderate to good yields with high (E)-selectivity.     

A Practical and General Base‐Catalyzed Carbonylation of Amines for the Synthesis of N‐Formamides

A highly practical and general base‐catalyzed carbonylation of amines to the corresponding N‐formamides has been realized. Cheap inorganic bases, including Group IA and IIA metal hydroxides, alkoxides, carbonates, and phosphates, were effective catalysts for the transformation. In the presence of 10–40 mol % of KOH or K₂CO₃, various amines were converted into the corresponding N‐formamides in good‐to‐excellent yields using CO as the formylation reagents.     

Thermal and microwave-assisted N-formylation using solid-supported reagents

A rapid and easy route to formamides by microwave assisted N-formylation of primary and secondary amines is described. Using an insoluble polymer or an inorganic solid-supported reagent as a formylating agent, microwave irradiation furnished the corresponding formamides in high yields, with reduced reaction time and solvent volume over the conventional approach.     

Betaine Catalysis for Hierarchical Reduction of CO2 with Amines and Hydrosilane To Form Formamides,Aminals, and Methylamines

An efficient, sustainable organocatalyst, glycine betaine, was developed for the reductive functionalization of CO₂ with amines and diphenylsilane. Methylamines and formamides were obtained in high yield by tuning the CO₂ pressure and reaction temperature. Based on identification of the key intermediate, that is, the aminal, an alternative mechanism for methylation involving the C⁰ silyl acetal and aminal is proposed. Furthermore, reducing the CO₂ amount afforded aminals with high yield and selectivity. Therefore, betaine catalysis affords products with a diversified energy content that is, formamides, aminals and methylamines, by hierarchical two‐, four‐ and six‐electron reduction, respectively, of CO₂ coupled with C−N bond formation.     

Betaine Catalysis for Hierarchical Reduction of CO2 with Amines and Hydrosilane To Form Formamides,Aminals, and Methylamines

An efficient, sustainable organocatalyst, glycine betaine, was developed for the reductive functionalization of CO₂ with amines and diphenylsilane. Methylamines and formamides were obtained in high yield by tuning the CO₂ pressure and reaction temperature. Based on identification of the key intermediate, that is, the aminal, an alternative mechanism for methylation involving the C⁰ silyl acetal and aminal is proposed. Furthermore, reducing the CO₂ amount afforded aminals with high yield and selectivity. Therefore, betaine catalysis affords products with a diversified energy content that is, formamides, aminals and methylamines, by hierarchical two-, four- and six-electron reduction, respectively, of CO₂ coupled with C−N bond formation.     

Stereoselective intramolecular 1,3-dipolar nitrile oxide cycloaddition reaction of N-formyl-β-nitroamides

The stereoselective intramolecular nitrile oxide cycloaddition (INOC) reaction was achieved from N-formyl-β-nitroamides, which were prepared through the Michael addition of allylic formamides to nitroalkenes, and cis-pyrroroisoxazoles and trans-piperidinoisoxazoles were obtained in a stereoselective manner.     

Tetrabutylammonium chloride-triggered 6-endo cyclization of o-alkynylisocyanobenzenes: an efficient synthesis of 2-chloro-3-substituted quinolines

A highly efficient one-pot synthesis of 2-chloro-3-substituted quinolines has been developed by tetrabutylammonium chloride-triggered 6-endo cyclization of o-alkynylisocyanobenzenes, which are generated in situ by dehydration of the corresponding N-(2-ethynylphenyl)formamides.     

Synthese von 4(5)-acyl-5(4)-alkylimidazolen aus symmetrischen 1,3-dicarbonylverbindungen

Synthesis of 4(5)-Acyl-5(4)-alkylimidazoles from Symmetrical 1,3-Diones A new synthesis of 4(5)-acyl-5(4)-alkylimidazoles 1 is described. The symmetrical 1,3-diones 5a and 5b were reacted with N₂O₄ to give the nitro compounds 7a and 7b , respectively; 5c was treated with NaNO₂ to give the nitroso compound 7c (Scheme 2). Hydrogenation of 7a , 7b and 7c over Pd/C in acetic acid/acetic formic anhydride yielded the formamides 9a , 9b and 9c , whose cyclization in formamide/formic acid afforded the 4(5)-acyl-5(4)-alkylimidazoles 1a, 1b and 1c , respectively. Oxazoles 11a and 11b were obtained from the corresponding formamides 9a and 9b with methanesulfonic acid/P₂O₅.     

Fluoride‐Catalyzed Methylation of Amines by Reductive Functionalization of CO2 with Hydrosilanes

An effective and inexpensive organocatalyst tetrabutylammonium fluoride (TBAF) was developed for the reductive functionalization of CO₂ with amines to selectively afford formamides or methylamines by employing hydrosilanes. Hydrosilanes with different substituents show discriminatory reducing activity. Thus, the formation of formamides and further reduction products, that is, methylamines could be controlled by elegantly tuning hydrosilane types. Formamides were obtained exclusively under an atmospheric pressure of CO₂ with triethoxysilane. Using phenylsilane as a reductant, methylamines were attained with up to 99 % yield at 50 °C coupled to a complete deoxygenation of CO₂. The crucial intermediate silyl formate in the formylation step was identified and thereby a tentative mechanism involving the fluoride‐promoted hydride transfer from the hydrosilane to CO₂/formamide was proposed. Striking features of this metal‐free protocol are formylation and methylation of amines by reductive functionalization of CO₂ with hydrosilanes and mild reaction conditions.     

A novel reductive coupling reaction between diphenylphosphine sulfide and formamides

The coupling reaction of diphenylphosphine sulfide with N,N-disubstituted formamides in the presence of an excess amount of sodium hydride proceeded smoothly to give the corresponding aminomethyldiphenylphosphine sulfides in good yields. This method is expected to provide a useful synthesis of P,N-containing ligands.     

Chiral 1,3-diamines from a lithiated isocyanide and chiral aziridines

Reaction of lithiated 4-methoxybenzylisocyanide with homochiral amino acid derived N-tosyl- and N-diphenylphosphinoylaziridines proceeds diastereoselectively to provide N-protected 3-isocyanoamines. Separation of the diastereomers of these adducts or the corresponding formamides, and subsequent transformations, lead to 1,3-diamines and their monoprotected and differentially bisprotected derivatives.     

The nature of the [C2H6N]+ and [CH4N]+ ions formed by electron impact on methylated formamides,acetamides, ureas,thioureas and hexamethylphosphoramide

By means of appearance potential measurements and metastable analysis, it is shown that the [C₂H₆N]⁺ and [CH₄N]⁺ ions formed from methylated formamides, acetamides, ureas and thioureas rearrange upon formation to structures similar to the [M? H]⁺ ions from mono- and dimethylamine.     

Efficient synthesis of β-enaminoesters via highly stereoselective Reformatsky reaction with disubstituted formamides as novel electrophiles

An efficient synthesis of various β-enaminoesters has been achieved via Reformatsky reaction with disubstituted formamides as novel electrophiles. The exclusive β-enaminoester E-isomers were obtained in 60-72% yield.     

The action of substituted formamides on arylformylacetonitriles

The reaction between phenyl- or p-methoxy phenylformylacetonitrile and monosubstituted formamides results in enaminonitriles. In some instances a simultaneous deformylation is observed. Formic acid is produced during the reaction and its origin was investigated.     

Reduction of isocyanates and carbodiimides via hydrosilylation

The hydrosilylation of isocyanates is promoted by palladium catalysts and affords N-silylformamides or C-silylamides. The orientation of the reaction depended upon the structure of isocyanates. The reaction of carbodiimides with silicon hydrides, catalyzed by PdCl₂ or (Ph₃P)₃RhCl, required higher temperatures to give N-silylformamidines. The adducts obtained in these reactions are precursors to formamides, formamidines, and their N-acetyl derivatives.     

Ultrasound-assisted tandem synthesis of tri- and tetra-substituted pyrrole-2-carbonitriles from alkenes,TMSCN and N,N-disubstituted formamides

An energy-saving and eco-friendly method for the efficient construction of various tri- and tetra-substituted pyrrolecarbonitriles through ultrasound-assisted multicomponent tandem reaction of readily available alkenes, TMSCN and N,N-disubstituted formamides within 40 min under metal-, solvent-free and mild conditions was developed. The dual role of iodine (catalyst and oxidant) notably simplified the reaction conditions and reduced the chemical waste generated     

A new synthesis of β-amino acids by use of ketene diethyl acetal as enolate equivalent

Reaction of phenylsulfonyl formamides, readily available in a single step from an aromatic aldehyde and sodium phenylsulfinate, with ketene diethyl acetal under basic conditions gives N-formyl β-amino acid esters in good yield, which can be kinetically resolved with a lipase.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

Copper-catalyzed oxidative coupling of carboxylic acids with formamides for the synthesis of α,β-unsaturated amides

A novel and efficient protocol for the synthesis of α,β-unsaturated amides has been developed using catalytic amount of Cu(OAc)₂ and TBHP as an available oxidant. Oxidative coupling of various unsaturated carboxylic acids with N,N-disubstituted formamides was examined to furnish the desired products in good yields.     

Unexpected formation of N,N-disubstituted formamidines from aromatic amines, formamides and trifluoroacetic anhydride

An intriguing selectivity towards the formation of the formamidine was observed upon the reaction of an amine with sodium hydride and trifluoroacetic anhydride in dimethyl formamide. Various aromatic amines were reacted with a series of N,N-disubstituted formamides as a solvent under the influence of trifluoroacetic anhydride to thoroughly probe this behaviour. A trend in selectivity is discussed and a proposed mechanism for the reaction is also presented.