Том 52, № 3 (2016)

Bromination–dehydrobromination of methyl (E)-3-(4-methylbenzenesulfonyl)prop-2-enoate gave methyl (Z)-3-bromo-3-(4-methylbenzenesulfonyl)prop-2-enoate whose structure was determined by X-ray analysis. Methyl (Z)-3-bromo-3-(4-methylbenzenesulfonyl)prop-2-enoate behaved as a synthetic equivalent of methyl 3-(4-methylbenzenesulfonyl)prop-2-ynoate in reactions with dimethyl malonate and methyl acetoacetate, which afforded the corresponding Michael adducts, trimethyl 3-(4-methylbenzenesulfonyl)prop-1-ene-1,1,2-tricarboxylate and dimethyl (Z)-2-acetyl-3-(4-methylbenzenesulfonyl)but-2-enedioate, respectively, via nucleophilic attack on the β-position with respect to the sulfonyl group.

Carbonic dihydrazide reacted with 2 equiv of trifluoroacetylacetone to give a compound containing 5-hydroxy-4,5-dihydropyrazole and keto enehydrazine fragments. Analogous 2 : 1 condensations of trifluoro-acetylacetone and 4-ethoxy-1,1,1-trifluorobut-3-en-2-one with oxalohydrazide and malonohydrazide afforded bis(5-hydroxy-4,5-dihydropyrazole) structures as two diastereoisomers.

The reaction of aryl(dichloro)phosphines with (2-chloroethoxy)trimethylsilane in the presence of haloacetic acid esters was studied with the goal of developing a new method for the synthesis of ethyl [(2-chloroethoxy)(4-dimethylaminophenyl)phosphoryl]acetate. The effect of various factors, such as substituent in the para position of the aromatic ring in the initial aryl(dichloro)phosphine, halogen nature in haloacetic acid ester, and chloro(trimethyl)silane, on the reaction course was analyzed.

Lewis acid-catalyzed reaction of (–)-caryophyllene oxide with phenylmethanethiol gave sulfides with clovane and caryophyllane structure which were oxidized to the corresponding sulfoxides and sulfones in 74 and 84% yield, respectively.

5-Aryl(hetaryl)furan-2,3-diones reacted with N-(triphenyl-λ⁵-phosphanylidene)-4,5,6,7-tetrahydro-1-benzothiophen-2-amines to give 5-aryl(hetaryl)-2-[(4,5,6,7-tetrahydro-1-benzothiophen-2-yl)imino]furan-3(2H)-ones whose acid hydrolysis afforded 4-aryl(hetaryl)-2-hydroxy-4-oxo-N-(4,5,6,7-tetrahydro-1-benzothiophen- 2-yl)but-2-enamides.

Two novel schemes have been developed for the synthesis of the C⁵–C¹⁴ fragment of the macrocyclic antitumor drug laulimalide and its analogs via transformations of cyclopropanol intermediates.

The Meerwein reaction of 1-methylquinolin-2(1H)-one with 4-acetylbenzenediazonium chloride gave 3-(4-acetylphenyl)-1-methylquinolin-2(1H)-one which was brominated to 3-[4-(2-bromoacetyl)phenyl]-1-methylquinolin-2(1H)-one. The latter reacted with pyridine, 4-methylpyridine, quinoline, benzo[f]quinoline, and triphenylphosphine to afford the corresponding quaternary salts, and its reactions with thioacetamide, thiourea, 2-aminopyridine, and 2-aminopyrimidine led to the corresponding thiazole, imidazo[1,2-a]pyridine, and imidazo[1,2-a]pyrimidine derivatives containing a 2-oxoquinoline fragment. 3-(4-{2-[2-(Arylmethylidene)-hydrazinyl]-1,3-thiazol-4-yl}phenyl)-1-methylquinolin-2(1H)-ones were obtained by condensation of 3-[4-(2-bromoacetyl)phenyl]-1-methylquinolin-2(1H)-one with thiosemicarbazide and aromatic aldehydes.

A number of new acridino[4,3-c]acridinedione derivatives have been synthesized for the first time by condensation of N¹,N⁵-bis(arylmethylidene)naphthalene-1,5-diamines with cyclic 1,3-diketones (cyclohexane-1,3-dione and dimedone). The product structure has been determined by two-dimensional NMR spectroscopy, and a probable reaction mechanism has been proposed.

3-Unsubstituted 4,5-dihydroisoxazoles obtained by nitrosation of arylcyclopropanes are capable of undergoing efficient isomerization into 3-aryl-3-hydroxypropanenitriles during chromatography on alumina.

According to HF and DFT quantum chemical calculations and ¹H NMR data, the chair–chair conformational equilibrium of 5-methyltetrahydro-1,3-oxazine shifts toward the conformer with equatorial orientation of the methyl group on C⁵ and axial orientation of the NH proton. 3,5-Dimethyltetrahydro-1,3-oxazine exists preferentially as chair conformer with equatorial orientation of the 5-methyl group; orientation of the N-methyl group almost does not affect the conformational equilibrium.

Regardless of the conditions, the condensation of 4-amino-2,4-dihydro-3H-1,2,4-triazole-3-thiones with aromatic aldehydes afforded the corresponding hydrazones as the only product. Both initial amines and resulting hydrazones exist as the thione rather than thiol tautomer. In no case bicyclic 5,6-dihydro[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles that are isomeric to the hydrazones were detected. DFT quantum chemical calculations at the B3LYP/6-31+g(d,p) level of theory with full geometry optimization showed that the hydrazone structure in methanol and DMF is more stable than the bicyclic isomer by 19–23 kcal/mol, which completely excluded the possibility for such cyclization. The thione tautomer of the hydrazones is more stable than the thiol structure by 11–13 kcal/mol.

A new reagent system consisting of aqueous KI₃ in AcOH and NaIO₄ as oxidant has been found to be effective in iodinating a variety of commercially important aromatic substrates under ambient conditions. The presence of Na₂SO₃ enhances the yield and the product purity. The procedure ensures high yields (72–98%) at room temperature in a short reaction time. A remarkable feature of this system is that even acidsensitive functionalities like anilines can be iodinated quantitatively.