Amides as precursors of imidoyl radicals in cyclisation reactions

Amides have been successfully used as precursors of imidoyl radicals for radical cyclisation. The amides have been converted to imidoyl selanides via reaction with phosgene to yield imidoyl chlorides followed by reaction with potassium phenylselanide. Imidoyl selanides were reacted with tributyltin hydride (Bu₃SnH) as the radical mediator with triethylborane or AIBN as initiators to yield imidoyl radicals for cyclisation reactions. Imidoyl radicals have been cyclised onto alkenes to yield 2,3-substituted-indoles and -quinolines and also onto pyrroles and indoles to give bi- and tricyclic heteroarenes.     

Copper-catalyzed synthesis of 1,2-disubstituted benzimidazoles from imidoyl chlorides

A strategy for the synthesis of 1,2-disubstituted benzimidazoles has been developed and a variety of 1,2-disubstituted benzimidazoles were obtained from imidoyl chlorides and o-haloanilines via copper(I)-catalyzed reaction in moderate yields.     

Fluorinated N-[2-(haloalkyl)phenyl]imidoyl chloride, a key intermediate for the synthesis of 2-fluoroalkyl substituted indole derivatives via Grignard cyclization process

Fluorinated N-[2-(haloalkyl)phenyl]imidoyl chloride, which was readily available from the corresponding anilines by using Uneyama's one-pot synthesis of fluorinated imidoyl chloride, was found to be a key intermediate for the facile synthesis of 2-fluoroalkyl substituted indole derivatives via the Grignard cyclization process. The bromination of 3-methyl group of 3-methyl-2-trifluoromethyl indole with NBS/CCl₄ led to the formation of 3-bromomethyl substituted indole which can be further utilized to synthesize some new and biologically interested indole derivatives.     

Convenient synthesis of 2-alkylamino-6-carboxy-5,7-diarylcyclopenteno[1,2-b]pyridines via direct acylamination with imidoyl chlorides

A robust synthetic method for 2-alkylamino-6-carboxy-5,7-diarylcyclopenteno[1,2-b]pyridines via acylamination at the alpha position of the functionalized pyridine system has been developed. The key step in this method was achieved by treatment of the corresponding pyridine N-oxides with 2.5 equiv of imidoyl chlorides in the presence of triethylamine, thus producing the desired 2-acylaminopyridines in good yields (74-96%).     

Synthesis of 2-aminooxazolines from isonitriles and iodine

A novel one-pot protocol for the synthesis of substituted 2-aminooxazoline from isonitriles and 2-aminoethanol was developed and the reactions involved imidoyl diiodide intermediates,which were generated by mixing isonitriles and iodine in CH₂C1₂ at room temperature.     

Polyheteroarenes based on aromatic imidoyl chlorides

Interaction of imidoyl chlorides with various diamines, bisphenols, and dicarboxylic acids was studied.     

Conformation analysis of isomers of imidoyl halides

The possible mechanisms of the intramolecular syn-anti isomerization of imidoyl halides have been analyzed with the aid of nonempirical quantum-chemical calculations. In the liquid phase isomerization can occur after a preliminary step of ionization with the formation of nitrilium cations. The conformational features have been studied by the methods of molecular mechanics, the differences between the energies of the syn and anti isomers of a number of imidoyl halides and closely related azomethines have been calculated, and the relative equilibrium concentrations of the isomeric forms at 298°K have been evaluated.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 21, No. 2, pp. 153–159, March–April, 1985.     

A two-step approach to 2-polyfluoroalkyl quinolines from N-aryl polyfluoroalkyl imidoyl iodides

2-Polyfluoroalkyl quinoline derivatives were synthesized from the enaminones which were obtained from the reaction of N-aryl polyfluoroalkyl imidoyl iodides with methyl ketones.     

Iron-catalyzed cross-coupling of imidoyl chlorides with Grignard reagents

[reaction: see text] A general, high yielding rapid iron-catalyzed cross-coupling reaction between Grignard reagents and imidoyl chlorides is described. These reactions are typically completed within 5 min, resulting in high yields of 71-96% using 5% iron catalyst in a THF-NMP solvent mixture. Functionalized imidoyl chlorides (e.g., R = CO(2)Me) gave excellent yields (89%).     

Formation of Dialkyl 2‐[3‐Alkoxy‐1‐(alkylimino)‐1‐chloro‐3‐oxopropan‐2‐ylidene]hydrazine‐1,1‐dicarboxylates of α‐(Alkoxycarbonyl)imidoyl Chlorides from PhosphineDiazo Ester Zwitterions and Nef‐Isocyanide Adducts

A novel transformation involving phosphine? diazo ester zwitterions (generated from dialkyl azodicarboxylates with Ph₃P) and α‐(alkoxycarbonyl)imidoyl chlorides (prepared from α‐addition of acyl chlorides to alkyl isocyanides) to afford dialkyl 2‐[3‐alkoxy‐1‐(alkylimino)‐1‐chloro‐3‐oxopropan‐2‐ylidene]hydrazine‐1,1‐dicarboxylates in moderate yields, is described.     

Stereoselective synthesis of 2-alkylidene-3-iminoindoles by reaction of 1,1-dianions with oxalic acid bis(imidoyl) chlorides

Treatment of dilithiated nitriles and sulfones with oxalic acid bis(imidoyl) chlorides resulted in a new cyclization reaction which provided a variety of (3-imino-2, 3-dihydro-1H-indol-2-ylidene)acetonitriles and -sulfones in good yields. The reactions proceeded by condensation of the dianions with the first imidoyl chloride group of the bis(imidoyl) chloride, subsequent intramolecular attack of the ortho carbon of the arylimino group onto the second imidoyl chloride group, and final aromatization. Excellent stereoselectivities were observed in most cases.     

Synthesis of 3‐Aryl‐5‐methyl 4‐Substituted [1,2,4]Triazoles

Treatment of N‐substituted acetamides with oxalyl chloride generates imidoyl chlorides, which react readily with aryl hydrazides. Following cyclization, triazoles can easily be obtained in moderate to good yields. 5‐Methyl triazoles can be further functionalized through α‐lithiation and subsequent reaction with an electrophile.     

Palladium-catalyzed synthesis of alpha-iminoamides from imidoyl chlorides and a carbamoylsilane

A series of pure imidoyl chlorides were converted into alpha-iminoamides by treatment with a carbamoylsilane under catalysis by palladium(0) complexes.     

Preparations and reactions of 2-trifluoromethylketenimines

Preparations and reactions of a series of 2-trifluoromethylketenimines are described. Trifluoromethylketenimines were prepared from trifluoropropanoic acids via corresponding imidoyl chlorides in good yields. 2-Trifluoromethylketenimine was functionalized at its β-position by electrophilic addition of halide, followed by dehydrohalogenation. Addition of nucleophile at α-position gave trifluoroethylated β-amino acid derivative via 1,3-proton shift.     

Facile synthesis of α-fluoro substituted amidines from imidoyl chlorides and some of its application

A series of α-fluoro subustituted amidines were synthesized from corresponding fluorinated imidoyl chlorides in good to excellent yields and some of its applications are outlined in our programs.     

New preparation method for Vilsmeier reagent and related imidoyl chlorides

An environmentally benign and inexpensive preparation method is described of some imidoyl chlorides, including the Vilsmeier reagent (VR), by using phthaloyl dichloride. Synthetic applications were demonstrated using the isolated VR or VR prepared in situ for the transformation of acids to acid chlorides, alcohols to chlorides, and the formylation of dimethylaminobenzene.     

An aryl to imidoyl palladium migration process involving intramolecular C-H activation

Biologically interesting fluoren-9-one and xanthen-9-one derivatives have been prepared by a novel aryl to imidoyl palladium migration, followed by intramolecular arylation. The fluoren-9-one synthesis appears to involve both a palladium migration mechanism and a C-H activation process proceeding through an unprecedented organopalladium(IV) hydride intermediate. The results from deuterium labeling experiments are consistent with the proposed dual mechanism.     

A convenient synthesis of 2-substituted indoles by the reaction of 2-(chloromethyl)phenyl isocyanides with organolithiums

The reaction of 2-(chloromethyl)phenyl isocyanides, readily available by dehydration of the respective N-[2-(chloromethyl)phenyl]formamides, with organolithiums produced 2-substituted indoles in satisfactory yields through addition of organolithiums to the isocyano carbon followed by intramolecular substitution reaction of the resulting imidoyl anion intermediates.     

One-pot synthesis of 2-imidazolines via the ring expansion of imidoyl chlorides with aziridines

We herein report a simple and convenient one-pot synthesis of highly substituted 2-imidazolines in a regiocontrolled and stereospecific matter through the ring expansion reaction of an imidoyl chloride with an aziridine, analogous to the Heine reaction.     

Acyclic N-phenylsubstituted polyimides based on imidoyl chlorides and dicarboxylic acids

Acyclic polyimides are prepared for the first time through the interaction of imidoyl chlorides and dicarboxylic acids. This transformation passes through the formation of polycarboxyimidates, which, depending on the temperature of reaction, rearrange in situ via the Mumm-Hess mechanism or during subsequent heating to yield the target product. The polymers thus prepared show high solubility and thermal stability (380–450°C).