Oxygen-atom transfer reagents: New, reactive α-azohydroperoxides

Synthesis and antiproliferative activity of some 3-(pyrid-2-yl)-pyrazolines

“…Attempts to purify these compounds by silica gel column chromatography however led to decomposition, as was previously observed with similar substrates, 22,23,26 possibly due to autoxidation. 27 Instead, the N-H pyrazolines 6 and 7 were treated directly with the desired electrophile to afford the Nsubstituted pyrazolines 8 and 9 which could be puried, in a one-pot transformation in good yields.…”

Pyrazol(in)e Derivatives of Curcumin Analogs As a New Class of Anti- Trypanosoma Cruzi Agents

“…The synthesis of unsubstituted pyrazolines 4a-e proved a challenging task, due to instability and decomposition of the products when dissolved in most organic solvents. This behavior was not unexpected, since it has been documented in the literature [28][29][30][31]. The two main obstacles we had to overcome in order to obtain a high purity product were: a) the autoxidation of the products upon exposure to the atmosphere [28,31] and b) the fact that they cannot be purified by chromatographic methods [29,30].…”

Alkylation of β-dicarbonyl compounds as a method for the production of functionally substituted dihydrofurans

“…The extracts were washed with water and dried over anhydrous MgSO 4 , the ether was distilled off, and the residue was distilled under vacuum. 1-Acetyl-1,2-di(ethoxycarbonyl)cyclopropane (7). From a mixture of acetoacetic ester (6.5 g, 0.05 mol), ethyl 2,3-dibromopropionate (13 g, 0.05 mol), and K 2 CO 3 (22 g, 0.16 mol) in DMSO (25 ml) we obtained 6 g (52.6%) of compound 7; bp 122-122.5°C (1 mm Hg), n D 20 1.4600.…”

“…Universal and convenient synthons for the "construction" of furans and related heterocycles containing an acyl group at position 3 of the heterocycle are β-dicarbonyl compounds. In recent years [2-4] a series of reviews have been published on numerous methods for the synthesis of furans from 1,3-diketones, which are valuable intermediates in the synthesis of liquid crystals, various heterocycles, and physiologically active substances and particularly pheromones and prostaglandins [5][6][7][8].We investigated the alkylation of some representatives of β-dicarbonyl compounds by various dihalides in order to obtain functionally substituted dihydrofurans.While continuing study of the reactivity of β-dicarbonyl compounds [9, 10] we realized the reactions of dimedone, allyl acetoacetate, acetylacetone, and acetoacetic ester with ethyl 2,3-dibromopropionate (1) and 1,4-dibromo-2-butene (2) in the K 2 CO 3 -DMSO system. It was established that the alkylation of dimedone with compounds 1 (Scheme 1) and 2 (Scheme 2) takes place exclusively in the direction of C,O-cycloalkylation with the formation of 2-ethoxycarbonyl-6,6-dimethyl-2,3,4,5,6,7-hexahydrobenzo[b]furan-4-one (3) and 6,6-dimethyl-2-vinyl-2,3,4,5,6,7-hexahydrobenzo[b]furan-4-one (9) respectively.…”

“…Universal and convenient synthons for the "construction" of furans and related heterocycles containing an acyl group at position 3 of the heterocycle are β-dicarbonyl compounds. In recent years [2][3][4] a series of reviews have been published on numerous methods for the synthesis of furans from 1,3-diketones, which are valuable intermediates in the synthesis of liquid crystals, various heterocycles, and physiologically active substances and particularly pheromones and prostaglandins [5][6][7][8].…”