卷 53, 编号 8 (2017)

Modern approaches to the synthesis of aromatic and heteroaromatic carboxylic acids and their esters based on the latest advances in organic chemistry are compiled and systematized in this review.

Reactions of adamantan-1(2)-amines and adamantan-1(2)-ylalkanamines with ethyl isothiocyanatoacetate afforded ethyl ({[adamantan-1(2)-ylalkyl]carbamothioyl}amino)acetates in 85–95% yields. The hydrolysis of ethyl {[(adamantan-2-yl)carbamothioyl]amino}acetate in alkaline medium resulted in the formation of {[(adamantan-2-yl)carbamothioyl]amino}acetic acid in a virtually quantitative yield.

Reaction of 1,1- and 1,2-dichloroethenes with Ph₂S₂, Ph₂Se₂, Bn₂S₂, and i-Pr₂S₂ in a system hydrazine hydrate–KOH proceeds as a sequence of successive transformations: dehydrochlorination of initial dichloroethenes to form chloroacetylene, chlorine substitution for the chalcogen-containing nucleophile (ethynylchalcogenides formation), and the addition of the nucleophilic reagent to the triple bond affording 1,2- dichalcogenylethenes. In reactions with PhS^– and PhSe^‒ nucleophiles due to the high rate of all stages 1,2-bis (phenylchalcogenyl)ethenes are obtained having mainly the Z-configuration. In reactions with BnS^‒ and i-PrS^‒ in the IR, NMR and chromato-mass spectra intermediate ethynylchalcogenides were identified, and the final products consisted of a mixture with the prevalence of the Z-isomer.

Reaction of 3-oxotriterpenoids and steroids with acrylonitrile in the presence of BnEt₃NCl and 30% KOH in dioxane proceeds with the formation of 2,2-biscyanoethyl derivatives substituted in the α-position to 3-oxo group. In the presence of several α-hydrogen atoms at the 3-oxo group the reaction of cyanoethylation involved the positions C⁴ and C⁵, leading to 2,2,5-tricyanoethyl and 2,4-dicyanoethyl derivatives. The cyanoethylation of tetracyclic compounds occurred with the formation of monocyanoethyl derivatives with an overall increase in the yield.

Rh₂(OAc)₄-catalyzed reaction of 2-(2-carbonylvinyl)-3-phenyl-2H-azirines with diazo esters proceeds through an intermediate generation of azirinium ylide suffering a nonstereoselective ring opening to form (3Z)- and (3E)-2-azahexa-1,3,5-trienes. The former depending on configuration of the C⁵=C⁶ bond may undergo cyclization either in derivative of 2,3-dihydropyridine, or in pyrrolium ylide that isomerizes into a derivative of 1H-pyrrole. According to DFT calculation, the preferred formation of pyrroles at increasing volume of Z-substituent at the atom C⁶ and of substituents at the atom C¹ of 2-azahexatriene occurs due to the destabilization of more sterically loaded transition states of 1,6-cyclization.

Aiming at the synthesis of new potentially pharmacologically active compounds combining in the molecule structures of thiosemicarbazone and 3-hydrazinylpropionic acid, we performed a regio- and stereoselective N²-functionalization of thiosemicarbazones of aromatic and heteroaromatic aldehydes by alkaline hydration of the corresponding (E)-N²-cyanoethyl derivatives (propanenitriles) prepared by a regioand stereoselective cyanoethylation with acrylonitrile. The hydration proceeds with the retention of the Econfiguration of the initial propanenitriles.

Reaction of 2-(hydroxyamino)-1-R-propan-1-one oximes with furfural in methanol afforded the corresponding α-furylnitrones. The cyclization of α-furylnitrones in alkaline medium results in the formation of 5-aryl(hetaryl)-2-(furan-2-yl)-1H-imidazol-1-oles.

Alkylation products were obtained from ethyl 2-(hydroxyimino)-7-methyl-3-oxo-5-aryl-2,3- dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidin-6-carboxylates at the treatment with alkyl halides, dimethyl sulfate, and diazomethane. Diazomethane alkylated the initial substrate at the oxygen atom of the carbonyl group of the thiazolidine fragment, the other reagents, at the oxygen atom of the hydroxyimino group.

Aminomethylation of guanidine hydrochloride with aqueous formaldehyde and simplest amino acids depending on the reagents ratio results in bicyclic hydrochlorides (1: 4: 2) or tricyclic iminium chlorides (1: 6: 3) that in their turn may be converted into internal salts: zwitter-ions or betaines respectively.

Reaction of tellurium tetrachloride with methyl propargyl ether proceeds regio- and stereoselectively to afford a product of anti-addition against the Markovnikoff’s rule in quantitative yield. The obtained compound was reduced by sodium metabisulfite into E,E-bis(3-methoxy-1-chloroprop-1-en-2-yl)ditellane.

The previously unavailable methyl 4-methoxy-3-methyl-5-(methylamino)thiophene-2-carboxylate was obtained by the one-pot procedure from a lithiated methoxyallene, methyl isothiocyanate, and methyl 2-bromoacetate.