A synthesis of 2-diazoacetyl-2 H-azirines was developed starting from 2 H-azirine-2-carbonyl chlorides, generated by Fe(II)-catalyzed isomerization of 5-chloroisoxazoles. 2-Diazoacetyl-2 H-azirines easily undergo reactions characteristic of α-diazo ketones with preservation of the azirine ring. Reactions with hydrohalogenic, carboxylic, and p-toluenesulfonic acids provide novel 1-(3-aryl-2 H-azirin-2-yl)-2-halo- and 2-(R-oxy)ethan-1-ones in good yields. The synthesized 2 H-azirines can offer many possibilities for chemical manipulation in heterocyclic synthesis, due to the presence of highly reactive azirine and the exocyclic C(O)-CHN or C(O)-CHX functionalities, which can show orthogonal or domino reactivity. The synthetic usefulness of the developed building blocks was demonstrated by the preparation of new types of heterocyclic dyads (azirine-oxazole, azirine-pyrazoline, azirine-thiazole, azirine-oxirane, pyrrole-oxazole) as well as an azirine chalcone analogue, 2-azidoacetyl-2 H-azirine, and 2-diazoacetylaziridine derivatives.

A stereoselective and high-yield synthesis of hexahydropyrrolo[3,4-b]pyrroles from tetramic acids and 2H-azirines under Cu(I)-NHC catalysis is developed. An unusual N-C2 azirine bond cleavage, initiated by a copper enolate, was rationalized in terms of a free radical reaction mechanism.

Various 2-oxygen-substituted 2H-azirine-2-carboxylic acid derivatives were synthesized in high yields under mild conditions from readily available precursors, 2-halo-2H-azirines and OH-reagents having pKa values in the range of 3-10. This reaction is the first example of substitution at the azirine carbon atom for which an unusual SN2'-SN2' cascade mechanism was revealed.

A method of furo-annulation of 4-hydroxy-2oxoquinoline-3-carboxylates with 3-arylazirines under Cu(II) catalysis was developed to synthesize a variety of 2,3dihydrofuro[3,2-c]quinolones bearing a carbamate group at the C2 position. The reaction involves an azirine ring opening across the N−C2 bond and formation of a dihydrofuran ring with the inclusion of two azirine carbon atoms, accompanied by a shift of the ester group to the nitrogen. The discovered reaction is the first example of the use of 2H-azirines for furo-annulation.

A metal-free scalable synthesis of functionalized ketenimines from alkyl α-(aryl/heteroaryl)-α-diazoacetates and alkyl isocyanides induced by blue light irradiation has been developed. The reaction proceeds at room temperature without any photocatalyst and provides ketenimines in moderate to good yields. Density functional theory (DFT) calculations and the experimental study showed that aryl(alkoxycarbonyl)carbenes in both singlet and triplet states can react with isocyanides but only the reaction of the former leads to the smooth formation of ketenimines. The obtained ketenimines were used for the synthesis of functionalized amidines under mild metal-free conditions.

The recombinant mRNAs with 5′-untranslated region, called omega leader, of tobacco mosaic virus RNA are known to be well translated in eukaryotic cell-free systems, even if deprived of cap structure. Using the method of primer extension inhibition (toe-printing), the ribosomal particles were shown to initiate translation at uncapped omega leader when its 5′-end was blocked by a stable RNA-DNA double helix, thus providing evidence for internal initiation. The scanning of the leader sequence and the formation of ribosomal 48S initiation complexes at the initiation AUG codon occurred in the absence of ATP-dependent initiation factor eIF4F, as well as without ATP. The latter results implied the ability of ribosomal initiation complexes for ATP-independent, diffusional wandering (also called bi-directional movement) along the leader sequence during scanning.

The Co­(III)-catalyzed reaction of 1,3-dicarbonyl compounds with 2-(diazoacetyl)-2H-azirines, prepared by a simplified procedure from 2H-azirin-2-carbonyl chlorides, led in high yields to the formation of 2-(diazoacetyl)­pyrroles, while leaving the diazoacetyl function intact. The intramolecular aromatic substitution reaction of 2-(diazoacetyl)­pyrroles, catalyzed by Cu­(OTf)2, provided selectively previously unknown benzo­[e]- and hetero­[e]-fused indol-7-oles in good yields. Formylation of benzo­[e]­indol-4-ol led selectively to the 5-formyl derivative, which is a good precursor for an unusual salen ligand and its Ni-complex. Triflates prepared from benzo­[e]­indol-4-oles gave various 4-substituted benzo­[e]­indoles carrying aryl, 2-thienyl, 2-pyridyl, and alkynyl groups, in excellent yields using cross-coupling reactions. 4-(2-Pyridyl)­benzo­[e]­indoles, upon treatment with BF3·Et2O/Et3N, afforded a new type of fluorescent boron complexes with large Stokes shifts.

A catalytic nucleophilic addition reaction of 3‐hydroxybenzofuran‐2‐carboxylic acid derivatives to 2H‐azirines for the high‐yield synthesis of NH‐aziridines with a 3‐coumaranone substituent has been developed. The Ph3PAuNTf2‐catalyzed reaction is diastereoselective to give predominantly (RS,SR)‐isomer of aziridine in good yield. The Ni(hfacac)2‐catalyzed reaction affords aziridines in up to 98% yield and low or moderate diastereoselectivity, which in some cases is opposite to that observed for the gold(I)‐catalyzed reaction. The Ph3PAuNTf2 works well for sterically hindered azirines as well as benzofurans bearing electron‐withdrawing groups, whereas Ni(hfacac)2 is the catalyst of choice for the preparation of aziridines having diazoacetyl substituent. The latter compounds can serve as substrates for the synthesis of fused aziridines via Buchner ring expansion reaction.magnified image