Exploiting the Nucleophilicity of NH Imines: Synthesis of Enamides from Alkyl Azides and Acid Anhydrides

Generation of N-H Imines from α-Azidocarboxylic Acids through Ru-Catalyzed Decarboxylation

A new method for the synthesis of N-H imines from α-azidocarboxylic acids was developed, which proceeds through decarboxylative C-C bond cleavage catalyzed by a commercial diruthenium complex ([CpRu(CO)₂]₂) under visible light irradiation at room temperature within several minutes. The reactive products undergo condensation, which forms cyclic trimers (2,4,6-trialkylhexahydro-1,3,5-triazines) or linear N,N'-bis(arylmethylidene)arylmethanediamines in quantitative yields. Alternatively, the N-H imines can be trapped with benzylamine and 2-(aminomethyl)aniline, providing stable N-benylimines and tetrahydroquinazolines, respectively. Subsequent oxidation of tetrahydroquinazolines produced quinazolines.

Reagent-controlled regiodivergence in the [3,3]-sigmatropic rearrangement of N-(acyloxy)enamides

A regiodivergent [3,3]-sigmatropic rearrangement of N-(acyloxy)enamides based on the N–O bond cleavage is achieved by changing reaction conditions.

Rhodium(iii)-catalyzed tandem reaction: efficient synthesis of dihydrobenzo thiadiazine 1-oxide derivatives

A tandem annulation reaction triggered by rhodium(iii)-catalyzed C–H bond functionalizations has been well developed for highly efficient synthesis of dihydrobenzo thiadiazine 1-oxide derivatives from free NH-sulfoximine and two-component benzyl azides.

One-Pot Synthesis of Trisubstituted Triazenes from Grignard Reagents and Organic Azides

A simple and versatile method for the preparation of linear, trisubstituted triazenes is reported. The procedure is based on the reaction of Grignard reagents with 1-azido-4-iodobutane or 4-azidobutyl-4-methylbenzenesulfonate. These organic azides enable the regioselective formation of triazenes via an intramolecular cyclization step. The new method can be used for the preparation of aryl, heteroaryl, vinyl, and alkyl triazenes. The synthetic utility of vinyl triazenes is demonstrated by acid-induced C-N, C-O, C-F, C-P, and C-S bond-forming reactions.

An Efficient Protocol to Synthesize N-Acyl-enamides and -Imines by Pd-Catalyzed Carbonylations

For the first time, the bidentate phosphinite ligand 1,2-bis(di-tert-butylphosphinoxy)ethane (tBu₂ POCH₂ CH₂ OPtBu₂ ) was synthesized. In the presence of this ligand, various N-acyl enamides were obtained in good yields and chemoselectivity by Pd-catalyzed carbonylation reaction of imines containing α-H. Meanwhile, imines without α-H could be transformed to N-acyl imines, which form highly hindered amides by straightforward addition of Grignard reagents.

Transition-metal-free, visible-light-induced oxidative cross-coupling for constructing β-acetylamino acrylosulfones from sodium sulfinates and enamides

A visible-light-induced, Rose Bengal catalyzed photoredox process for synthesizing β-acetylamino acrylosulfones has been discovered.

In situ generation of N-unsubstituted imines from alkyl azides and their applications for imine transfer via copper catalysis

Although azides have been widely used in nitrene transfer reactions, in situ generation of N-H imines from azides for downstream transformations has rarely been explored. We report copper-mediated formation of N-unsubstituted aliphatic imines from easily available aliphatic azides using a customized phenanthroline-based ligand (L₁*). Through trapping in situ-generated N-H imines, multisubstituted pyridines or indoles were readily synthesized. ¹³C-labeled azide was used as part of an isotope labeling study, which suggests that the construction of pyridine derivatives involves a three-component dehydrogenative condensation. The construction of 2,3,5-triaryl pyridines using this method provided evidence supporting a proposed pathway involving both imine formation and abnormal Chichibabin pyridine synthesis. The generation of N-unsubstituted imine intermediates was also confirmed by formation of indole derivatives from alkyl azides.

Synthesis of 1H-azadienes and application to one-pot organic transformations

1H-Azadienes were synthesized from allyl azides by ruthenium catalysis under mild and neutral conditions. Applications of the 1H-azadienes were demonstrated for the one-pot synthesis of nitrogen containing organic compounds.

Catalytic transformation of esters of 1,2-azido alcohols into α-amido ketones

The esters of 1,2-azido alcohols were transformed into α-amido ketones without external oxidants through the Ru-catalyzed formation of N–H imines with the liberation of N₂ followed by intramolecular migration of the acyl moiety.