I. M. Sakhautdinov

SYNTHESIS OF PYRAZOLES BASED ON FUNCTIONALIZED ALLENOATES

Regiospecific synthesis of pyrazole-3-carboxylate derivatives by 1,3-dipolar cycloaddition of diazomethane with allenoates in presence of triethylamine is demonstrated. Reaction of allenoates with stearic acid moiety containing diazoketone is explored under ultrasonic conditions. Novel derivatives of pyrazole were achieved in excellent yields. INTRODUCTION Among compounds containing nitrogen heterocyclic frameworks, pyrazole is one of most useful building blocks for various biologically active molecules. The biological activities of these compounds have been widely used as antidiabetic, antiviral, antimicrobial, antibacterial, anticancer agents. In addition to their biological importance, pyrazoles play important role as catalysts, molecular magnetic devices and sensors. 1,3-Dipolar cycloaddition reactions of diazo compounds to double and triple bonds are well known and documented. In contrast, studies including this methodology with regard to allenes have received much less attention. In consideration of biological activity of compounds bearing the pyrazole moiety we planned the synthesis of series of pyrazole derivatives from functionalized allenoates. RESULTS AND DISCUSSION Allenoates 2a-f were obtained from N-phthalyl amino acids 1a-c and fatty acids 1d-f. Thionyl chloride was used to convert acids 1a-f to their corresponding acid chlorides. The reaction of acid chlorides with HETEROCYCLES, Vol. 89, No. 3, 2014 641

Synthesis of New Pyrazole–Methylmaleopimarate Conjugates

Regiospecific synthesis of conjugates containing a diterpenoid fragment and a pyrazole-ring pharmacophore by 1,3-dipolar cycloaddition of diazomethane to allenoates in the presence of Et3N was demonstrated.

Synthesis of isoindolo[2,1-b]isoquinoline-5,7-dione via the wittig intramolecular cyclization

Isoindoloisoquinoline contains two pharmacophore fragments and therefore serves as major structural fragment of a number of biologically active compounds used in clinical practice [1]. Isoquinoline alkaloids are widespread in nature [2, 3]. Recently, nuevamine [4], jamtine [5], and hirsutine [6] alkaloids inclusing isoindolo[1,2-a]isoquinoline fragment have been isolated from Cocculus hirsutus (L.) and Berberis darwinii Hook plants. Isoindolo[1,2-a]isoquinoline derivatives can be obtained from isoquinoline [7] and isoindole [8] derivatives. However, these methods utilize the poorly accessible starting materials.

Thermal oligomerization of methyl 4-(1,3-dioxo-2,3-dihydro-1H-isoindol-2-yl)buta-2,3-dienoate

Dimeric compounds formed as a result of thermal oligomerization of methyl 4-(1,3-dioxo-2,3- dihydro-1H-isoindol-2-yl)buta-2,3-dienoate were identified.

Synthesis of 1,2,3-Triazole Derivatives from 2,3-Dienoates of Methyl Maleopimarate

Hybrid compounds based on N-maleopimarimides containing a triazole-ring pharmacophore were prepared via 1,3-dipolar cycloaddition of methyl-2-azidoacetate to allenoates.

Cyclopentene-fused [C60]-fullerenes: synthesis and electrochemical properties

New cyclopentene-fused [C60]-fullerene derivatives containing terpene moieties have been synthesized by [3 + 2]-addition to fullerene C60. All obtained products were fully characterized by 1H- and 13C-NMR, IR, and MS. The electrochemical properties have been studied by cyclic voltammograms (CV), combined with absorption spectra, which are consistent with those obtained from density functional theory (DFT) calculations. It was found that all fulleropyrrolidines showed very similar absorption spectra, orbital energies, in which electron densities in both the LUMO and HOMO are mainly located on the fullerene cage, suggesting that C60 act as the acceptor. All the compounds exhibited good thermal stability. All determined characteristics of fullerene conjugates were compared to [6,6]-phenyl-C61-butyric acid methyl ester ([60]PCBM), a popular fullerene-containing compound.Graphical abstract

Effective Synthetic Method and Rotameric Isomerization of 2,4-Dioxo-1,2,3,4-Tetrahydropyrimidine-5-Maleopimarate

Maleopimaric acid and its derivatives exhibit potent biological activities, in particular, antiviral, antibacterial, cytotoxic, antitumor, and antiulcerogenic [1–5]. Proposed thermal-activation approaches to synthesizing N-imides of the methyl ester of maleopimaric acid (MEMPA) did not always lead to the target products and acceptable MEMPA conversion [6–9]. Herein, we communicate an effective synthetic method for N-maleopimarimide-substituted 5-aminouracil using ultrasound irradiation in dimethylsulfoxide (DMSO). Maleopimarimide 1 was synthesized in 18% yield by direct fusion of MEMPA (3) and 5-aminouracil (2) (Scheme 1). However, condensation in DMSO using a two-fold excess of 2 increased the yield of target product to 69% (Table 1). The best result was observed with a two-fold excess of 2 and ultrasound irradiation, which increased the yield of target product and shortened the reaction time (Table 1). The yield of final product was not affected if a large excess of 2 and longer irradiation times were used. The structure of 1 was elucidated using PMR and 13C NMR spectra. Proton resonances were fully assigned using 1H–13C HSQC. Then, correlations in 1H–13C HMBC mode between the terpene fragment of 1 and the pyrimidine moiety confirmed that the target product formed. PMR and 13C NMR spectra in various solvents [CDCl3, (CD3)2CO, DMSO-d6] exhibited doubled resonances for both the pyrimidine moiety and most of the maleopimarate resonances of 1. This indicated that two isomers were present (Table 2). Dynamic NMR spectroscopy in the range 20–100°C in DMSO-d6 showed that resonances coalesced at 80°C and that the barrier to rotation of the pyrimidine moiety relative to the maleopimarimide fragment disappeared at 100°C (Fig. 1). In our opinion, stable rotational isomers formed because of steric hindrance between the imide ketones and the pyrimidine moiety. Compound 3 was synthesized by the literature method [10]. Its physicochemical characteristics agreed with those in the literature.

Synthesis of Methyl Maleopimarates with Adamantyl Substituents

Conjugates with adamantyl substituents were synthesized as potentially biologically active compounds via the reaction of aminoadamantane with the anhydride of methyl maleopimarate (MMP) and with the N-maleopimarimide-substituted acid chlorides of α-alanine, β-alanine, valine, and γ-aminobutyric acid.

Fullerene C60 derivatives as efficient sensitizers of oxidation under the mild conditions of atmospheric air

The ability of fullerene C60 and of its derivatives to sensitize oxidation of triphenylphosphine with atmospheric oxygen under sunlight illumination at room temperature was found. Reuse of fullerene conjugates did not lead to reduction in their reactivity; the conjugates were recovered unchanged from the reaction mixture. The use of a xenon lamp significantly shortened the time of the process.

Ionic Liquid-Catalyzed and Microwave-Assisted Syntheses of Pyrrolizine- and Indolizinedione Derivatives

Abstract3H-Pyrrolo[2,1-a]isoindole-2,5-diones and isoindolo[2,1-a]quinoline-5,11-diones were synthesized by intramolecular cyclization of N-[2-oxo-3-(triphenyl-λ5-phosphanylidene)propyl]- and N-[2-(triphenyl-λ5-phosphanylidene)acetyl]phthalimides, respectively, in the presence of ionic liquid ([bmim][BF4], 10 mol %) as catalyst or under microwave irradiation.