M. Yu. Ievlev

Glycine catalyzed diastereoselective domino-synthesis of 6-imino-2,7-dioxabicyclo[3.2.1]octane-4,4,5-tricarbonitriles in water

The first example of glycine-catalyzed direct domino synthesis of 6-imino-2,7-dioxabicyclo[3.2.1]octane-4,4,5-tricarbonitriles in aqueous medium is described, giving products in excellent yields and moderate to excellent diastereoselectivities. This approach provides a highly efficient and environmentally benign access to cyano-substituted 2,7-dioxabicyclo[3.2.1]octane.

Synthesis of photochromic 5,6-diaryl-2-chloropyridine-3,4-dicarbonitriles from 3,4-diaryl-4-oxobutane-1,1,2,2-tetracarbonitriles

We now propose a new synthetic approach to photochromic diarylethenes, which is based on the reaction of tetracyanoethylene with ketones as key intermediate step. Tetracyanoethylation of ketones has been well documented; however, there are almost no published data on reactions of aryl arylmethyl ketones with tetracyanoethylene. Adducts of tetracyanoethylene with ketones of the general formula R(CO)CH2R′ were used as starting compounds to obtain heterocycles containing an RC=CR′ fragment [4–10]. Analogous reactions with aryl arylmethyl ketones Ar(CO)CH2Ar could give rise to various 1,2-diarylethenes as new potential photochromes. We were the first to react tetracyanoethylene with 1,2-diarylethanones Ia and Ib in the presence of a catalytic amount of hydrochloric acid. As a result, we isolated 3,4-diaryl-4-oxobutane-1,1,2,2-tetracarbonitriles IIa and IIb. The substrates were deoxybenzoin (Ia), the parent compound of the 1,2-diarylethanone series, and 1,2-bis(2,5-dimethylthiophen-3-yl)ethanone (Ib). The latter was selected taking into account that diarylethenes containing thienyl substituents are most promising from the viewpoint of the design of practically useful photochromic devices [1]. Ketone Ib was synthesized in a number of steps starting from hexane2,5-dione [11].

Domino-synthesis and fluorescence properties of 4-cyano-2-oxo-1,2-dihydropyridine-3-carboxamides and 2-oxo-1,2-dihydropyridine-3,4-dicarbonitriles

Non-catalytic conversion of 4-oxoalkane-1,1,2,2-tetracarbonitriles in the presence of water leads to the formation of a mixture of fluorescent 4-cyano-2-oxo-1,2-dihydropyridine-3-carboxamides and 2-oxo-1,2-dihydropyridine-3,4-dicarbonitriles in equal proportions. This transformation was explained, spectral-luminescence properties were investigated, and fluorescence quantum yield was measured.

Synthesis and solid-state fluorescence of aryl substituted 2-halogenocinchomeronic dinitriles

Based on the reaction of available adducts of tetracyanoethylene (TCNE) and aromatic ketones (4-aryl-4-oxoalkane-1,1,2,2-tetracarbonitriles) with hydrogen chloride, several aryl substituted 2-halogencinchomeronic dinitriles were synthesized. We found that aryl substituted derivatives, in contrast to alkyl substituted ones, possess an intensive solid state fluorescence. The relationship between the chemical structures and photophysical properties of these compounds was investigated.

Synthesis, solution and solid-state fluorescence of 2-diethylaminocinchomeronic dinitrile derivatives

A facile approach to the synthesis of novel 2-diethylaminocinchomeronic dinitriles, which are found to be fluorescent both in the solution and in a solid states, was developed. Absorption, fluorescence and solvatochromic properties as well as a crystal structure of the synthesized compounds were investigated. It was found that the 2-diethylaminocinchomeronic dinitrile derivatives with methoxy groups in the aryl moiety possess the most intensive emission in nonpolar solvents with fluorescence quantum yields up to 0.59.

Solvent-free synthesis of 4-oxoalkane-1,1,2,2-tetracarbonitriles

Problems related to directed synthesis of complex functionalized heterocyclic compounds constitute an important field of modern organic chemistry. Target structures may be constructed in several steps via successive introduction of particular substituents. However, this approach is often associated with low conversion of initial reactants, high expenditures of time, energy, and labor, the necessity of isolation and purification of intermediate products in every step, and other difficulties. These difficulties can be avoided by using special substrates capable of reacting in a domino (cascade) mode which implies that several consecutive chemical transformations can be accomplished as a single synthetic operation. Examples of such compounds are 4-oxoalkane-1,1,2,2-tetracarbonitriles 1 which were successfully used as starting compounds in the synthesis of difficultly accessible heterocyclic systems [1–6]. Up to now, more than 20 types of heterocycles have been obtained on the basis of 4-oxoalkane-1,1,2,2-tetracarbonitriles 1, and some compounds have been found to possess practically useful properties (e.g., fluorescence), which determines the importance of studies in this line [1].

Synthesis of 2-methoxypyridine-3,4-dicarbonitriles and 4-methoxy-2,3-dihydro-1H-pyrrolo[3,4]pyridine-1,3-diones

2-Halopyridine and its derivatives are convenient initial compounds for the synthesis of functional pyridine derivatives through reactions of nucleophilic substitution SNAr [1–3]. Some of forming compounds possess practically important properties, in particular, 2-hydroxypyridines (tautomers of pyridin-2-ones) are characterized by intense fluorescence [4, 5], and 2-alkoxypyridines exhibit antiphlogistic activity of a wide range of action [6]. We explored the reactions of 2-chloropyridne-3,4dicarbonitriles 1а–1с [7–9] with sodium methoxide. Initial compounds 1а–1с contain two cyano groups which considerably facilitate the nucleophilic substitution of halogen but also can suffer transformation under the action of nucleophiles [10]. The presence in the structure of pyridines 1а–1с of several competing sites for the attack of О-nucleophiles requires a development of special conditions for carrying out desired transformations. The reactions in the anhydrous methanol afford exclusively 2-methoxy derivatives 2а–2с in 68‒79% yields (Scheme 1). ISSN 1070-4280, Russian Journal of Organic Chemistry, 2015, Vol. 51, No. 11, pp. 1668–1670.

Synthesis of fluorescent alkoxybenzylidene derivatives of malononitrile dimer in water in the presence of Triton X-100

An efficient procedure has been developed for the synthesis of alkoxybenzylidene derivatives of malononitrile dimer in water in the presence of nonionic surfactant (Triton X-100). Depending on the number and position of alkoxy groups, the products showed solid-state fluorescence with the emission maximum in the range λ 491–560 nm.

Synthesis and solid-state fluorescence of 2-alkylamino-4-aminopyridine-3,5-dicarbonitriles

Reactions of 4-amino-2-aryl-6-chloropyridine-3,5-dicarbonitriles with primary and secondary amines afforded 2-alkylamino-4-amino-6-arylpyridine-3,5-dicarbonitriles which showed solid-sate fluorescence in the violet or blue region with the emission maxima in the λ range 400–460 nm.

Synthesis of photochromic maleimides containing dithienylethene and azobenzene fragments

Maleimides containing dithienylethene and azobenzene fragments have been synthesized by reaction of dithienyl-substituted maleic anhydrides with 4-aminoazobenzene in boiling toluene in the presence of triethylamine, and their photosensitivity has been studied.