L. B. Romanova

THERMOCHEMICAL STUDY OF SOME CUBANE DERIVATIVES

The thermochemical study of cubane-1,4-dicarboxylic acid (1), diethyl cubane-1,4-dicarboxylate (2), diisopropyl cubane-1,4-dicarboxylate (3), and bis(2-fluoro-2,2-dinitro)ethyl cubane-1,4-dicarboxylate (4) was performed. The standard enthalpies of combustion (ΔcH°) and formation (ΔfH°) of these compounds were estimated using the method of combustion in a calorimetric bomb in an oxygen atmosphere. Using the additive group method, calculated values for ΔfH° of these substances which agreed satisfactorily with the experimental ones were obtained. The strain energies (Es) of the cubic structure of derivatives1–4 were calculated. It was concluded thatEs did not change on substitution of hydrogen atoms in cubane for various functional groups and was equal toEs of the structure of cubane itself. The reliability of the single published value of ΔfH° in the cubane crystal state, 541.8 kJ mol−1 (129.5 kcal mol−1), was confirmed.

Synthesis of nitroxyalkylammonium nitrates

A method forO-nitration of amino alcohols with a non-detonating mixture of nitric acid with dichloromethane has been proposed. The target crystalline products were precipitated from the reaction mixture by acetic anhydride.

Energetic properties and impact sensitivity of crystalline explosives

The impact sensitivity of some groups of nitrates and cubane derivatives has been correlated with their heat of explosion and chemical structure. These correlations show the ways of reducing explosion hazard in handling these compounds. It is currently impossible to construct a reference series of compounds that would allow explosives with preset sensitivity to be synthesized on the basis of a preliminary energetic prediction. New opportunities to enhance safety in handling explosives can be provided by investigating their detonation ability.

Nitration of cubane-1,4-dicarboxylic acid dimethyl ester by dinitrogen tetraoxide

A first direct nitration of C—H bond of cubane-1,4-dicarboxylic acid dimethyl ester by dinitrogen tetraoxide at ∼20 °C has been carried out. During the nitration no rearrangement of cubane skeleton has been observed.

Cubane derivatives: 8. Synthesis of nitroxyalkyl-substituted cubane-1,4-dicarboxamides and 4-bromocubanecarboxamides

New substituted cubane-1,4-dicarboxamides and 4-bromocubanecarboxamides containing the nitroxyl group and amino acid fragments along with the cubane skeleton were synthesized. The cardiac pharmacological activity (both the effect on aorta relaxation and the calcium channel blocking activity) of most of nitroxyalkyl derivatives is equal to or higher than that of N-(2-nitroxyethyl)nicotinamide (nicorandil).

CUBANE DERIVATIVES. 3. SYNTHESIS AND ANTIISCHEMIC ACTIVITY OF SOME NITROXYALKYL DERIVATIVES OF 1,4-CUBANEDICARBOXYLIC ACID AND ITS DIAMIDE

NewN,N′-bis- andN,N,N′, N′-tetrakis-hydroxyalkyl-substituted 1,4-cubanedicarboxamides were synthesized. Nitration of these compounds yielded the corresponding nitrates. The reaction of 1,4-cubanedicarboxylic acid dichloride with ethylene glycol mononitrate and glycerol dinitrate gave ester 1,4-[R1R2CHOC(O)]2C8H6, where R1=H and R2=CH2ONO2; and R1=R2=CH2ONO2, respectively. The cardiopharmacological activity of some of the synthesized compounds was determined. This allowed us to find for the first time cubane derivatives that exhibit this kind of biological activity. The antiischemic activity of one of these compounds,N,N′-bis(2-nitroxythyl)-1,4-cubanedicarboxdiamide, is higher than that of the well-known Nicorandil.

Cubane derivatives 1. Synthesis and molecular structures of the esters of 1,4-cubanedicarboxylic acid

An effective method of esterification of 1,4-cubanedicarboxylic acid with alkylsulfuric acids is proposed. The derivatives of alkanols with substantially different pKa Valus are obtained in high yields. Molecular structures of the esters obtained are confirmed by various methods. The X-ray study showed a remarkable effect of the nature of an alkyl radical on the geometry of the cubane core.

Synthesis of 4-bromocubane-1-carbaldehyde

Oxidation of 4-bromo-1-hydroxymethylcubane and 1,4-bis(hydroxymethyl)cubane with the 2,2,6,6-tetramethylpiperidine-N-oxyl-trichloroisocyanuric acid-sodium bicarbonate system afforded the corresponding aldehydes. 4-Bromocubanecarbaldehyde was also obtained in high yield by reduction of 4-bromocubanecarboxylic acid and its methyl ester with bis(N-methylpiperazinyl)aluminum hydride.

CUBANE DERIVATIVES. 3. SYNTHESIS AND MOLECULAR STRUCTURE OF 1,4-BIS(HYDROXYMETHYL)CUBANE

An efficient procedure for the preparation of 1,4-bis(hydroxymethyl)cubane by reduction of cubane-1,4-dicarboxylic acid or its dimethyl ester with aluminum hydride was developed. The molecular structure of 1,4-bis(hydroxymethyl)cubane was established by X-ray diffraction analysis.

Synthesis and aminomethylation of some heterocyclic α-nitroxyalkyl NH acids

The recently discovered synthetic route to quaternary ammonium salts of a new series via N-aminometylation of 4,4-bis(nitroxymethyl)oxazolidin-2-one was extended to other NH acids obtained for the first time by O-nitration of known a-hydroxyalkyl derivatives of 4-methyloxazolidin-2-one, pyrrolidin-2-one, and benzimidazole. In the aminomethylation of these NH acids, dimethylamine and morpholine were used as the amine components.