Reactivity of thienopyrroles. Synthesis of isomeric nitro and bromothienopyrroles

The preparation of ethyl 2-bromothieno[2,3-b]pyrrole-5-carboxylate, ethyl 2-bromothieno[3,2-b]pyrrole-5-carboxylate, ethyl 2-nitrothieno[2,3-b]pyrrole-5-carboxylate and ethyl 2-nitrothieno[3,2-b]pyrrole-5-carboxylate are described.     

Nitration of furan derivatives with acetyl nitrate

The mixture of products formed in the nitration of methyl furan-2-carboxylate in acetic anhydride was separated by means of thin-layer and column chromatography. It was found that products of cis and trans addition of acetyl nitrate to the furan ring — methyl 5-nitro-2-ace-toxy-2,5-dihydrofuran-2-carboxylate and 5-nitro-4-acetoxy-4,5-dihydrofuran-2-carboxylate — and methyl 5-nitrofuran-2-carboxylate are formed in the nitration.     

Synthesis and alkylation of new functionally substituted 4,4-dimethylpiperidin-2-ones

The reaction of ethyl isopropylidenecyanoacetate with ethyl 3-amino-3-thioxopropanoate gave rise to ethyl 4,4-dimethyl-6-oxo-2-thioxo-5-cyanopiperidine-3-carboxylate whose alkylation provided ethyl 2-benzylsulfanyl-4,4-dimethyl-6-oxo-5-cyano-1,4,5,6-tetrahydropyridine-3-carboxylate, ethyl 5-benzyl-2-benzylsulfanyl-4,4-dimethyl-6-oxo-5-cyano-1,4,5,6-tetrahydropyridine-3-carboxylate, and ethyl 7,7-dimethyl-5-oxo-6-cyano-3,5,6,7-tetrahydro-2H-thiazolo[3,2-a]pyridine-8-carboxylate.     

5-(4-叔丁氧基羰基哌嗪基)苯并呋喃-2-甲酸乙酯的合成

5-溴苯并呋喃-2-甲酸乙酯与4-叔丁氧基羰基哌嗪进行Buchwald-Hartwig偶联反应,若催化剂是Pd(OAc)2/BINAP,碱是Cs2CO3,则产物主要是5-(4-叔丁氧基羰基哌嗪基)苯并呋喃-2-甲酸乙酯,转化率达70%;若催化剂是Pd(dba)2/P(t-Bu)3,碱是叔丁醇钾,则产物中几乎没有5-(4-叔丁氧基羰基哌嗪基)苯并呋喃-2-甲酸乙酯.文中讨论了影响这个Buchwald-Hartwig偶联反应的因素.     

Synthesis of fluoromethyl,difluoromethyl and trifluoromethyl analogues of pyrazosulfuron-ethyl as herbicides

Ethyl 1-fluoromethyl-5-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)pyrazole-4-carboxylate 1b , a new fluoromethyl analogue of the herbicide pyrazosulfuron-ethyl la, was prepared from ethyl 1-fluoromethylpyrazole-4-carboxylate 4b . The difluoromethyl and trifluoromethyl analogues 1c,d were also synthesized from ethyl pyrazole-4-carboxylate 2 via difluorocarbene reaction.     

Double rearrangement in the pyrrolidine-1,2-oxide system leading to pentasubstituted pyrroles.

Acid catalyzed double rearrangement of the ethyl 6-oxa-2,2, 4,4-tetramethyl-1-azabicyclo[3,1,0]hexane-3-carboxylate leading to ethyl 1,2,4,5-tetramethyl-pyrrole-3-carboxylate is proposed on the basis of identification of the intermediate ethyl 5-hydroxy-1,2,4,4-tetramethylpyrroline-3-carboxylate.     

Synthesis and ring opening reactions of a 2-silabicyclo[2.1.0]pentane

Methyl 2-silabicyclo[2.1.0]pentane-1-carboxylate, obtained by a photochemical intramolecular cyclopropanation reaction of an [small alpha]-allylsilyl-[small alpha]-diazoacetate, undergoes ring opening reactions under different conditions leading to methyl 2-[diisopropyl(methoxy)silylmethyl]cyclopropane-1-carboxylate, a 1-sila-4-cyclopentene-2-carboxylate or an allyl(methoxysilyl)ketene.     

Asymmetric synthesis of (alphaR)-polyfluoroalkylated prolinols based on the perfluoroalkyl-induced highly stereoselective reduction of perfluoroalkyl N-Boc-pyrrolidyl ketones

Reduction of the obtained chiral (S)- tert-butyl 2-(perfluoroalkanoyl)pyrrolidine-1-carboxylate with sodium borohydride or lithium aluminum hydride proceeded smoothly to give the corresponding (S)- tert-butyl 2-((R)-perfluoro-1-hydroxyalkyl)pyrrolidine-1-carboxylate in yields of 73-97% with excellent diastereoselectivities (up to >98% de), compared with the reduction of nonfluorinated (S)-tert-butyl 2-pentanoylpyrrolidine-1-carboxylate.     

A convenient synthesis of 5-fluorofuran-2-carboxylic acid

A convenient synthesis of 5-fluorofuran-2-carboxylic acid has been achieved in two steps and 56% total yield. Fluorodenitration of commercially available benzyl 5-nitrofuran-2-carboxylate utilizing potassium fluoride and catalytic tetraphenylphosphonium bromide in sulfolane at 140 °C for 2 h furnished benzyl 5-fluorofuran-2-carboxylate. Hydrogenolysis of benzyl 5-fluorofuran-2-carboxylate gave the title compound.     

Synthesis of halosulfuron-methyl via selective chlorination at 3- and/or 5-position of pyrazole-4-carboxylates

Reactions of methyl pyrazole-4-carboxylates 4b-d with N-chlorosuccinimide under heating conditions without a solvent gave methyl 3,5-dichloro-1-methylpyrazole-4-carboxylate 4a in good yields. The reaction of 4a with sodium hydrosulfide led to a nucleophilic substitution on the 5-position regioselectively to afford methyl 3-chloro-1-methyl-5-mercaptopyrazole-4-carboxylate 6a, which was followed by oxidative chlorination and amination to obtain 3-chloro-1-methyl-5-sulfamoylpyrazole-4-carboxylate 2a. Finally, the reaction of 2a with phenyl 4,6-dimethoxypyrimidin-2-yl carbamate 7 provided methyl 3-chloro-5-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-1-methylpyrazole-4-carboxylate (halosulfuron-methyl) 1a promising herbicide in com.     

Stereoselective syntheses of the three isomers of ethylene glycol bis(tropane-3-carboxylate)

Three epimers of ethylene glycol bis(tropane-3-carboxylate) (3alpha,3alpha'-, 3alpha,3beta'-, 3beta,3beta'-) have been synthesized by starting from 3-tropinone. 3-Tropinone was converted into the corresponding enol triflate and then subjected to palladium-catalyzed alkoxycarbonylation to provide the key intermediate methyl trop-2-ene-3-carboxylate in good yield. Stereoselective routes were developed to afford the three stereoisomers of ethylene glycol bis(tropane-3-carboxylate).     

Isomérisation thermocatalytique des esters cyclopropéniques

The thermocatalytic isomerisation of ethyl 1-methyl-2-phenyl-1-cyclopropene-3-carboxylate, ethyl 1-methyl-2-n-butyl-1-cyclopropene-3-carboxylate and ethyl 1-methyl-2-t-butyl-1-cyclopropene-3-carboxylate to furan derivatives has been studied and a mechanism for this isomerisation has been proposed.     

Synthesis and application of ethyl 2-arylazo-4,9-dioxonaphtho[2,3-b]thiophene-3-carboxylate

Synthesis of ethyl 2-arylazo-4,9-dioxonaphtho[2,3-b]thiophene-3-carboxylate was achieved by diazotization of ethyl 2-amino-4,9-dioxonaphtho[2,3-b]thiophene-3-carboxylate and coupling with selected N,N-dialkylanilines. The key intermediate ethyl 2-amino-4,9-dioxonaphtho[2,3-b]thiophene-3-carboxylate was synthesized by the condensation of sodium salt of ethyl cyanoacetate with 2,3-dichloro-1,4-naphthoquinone. Ethyl 2-arylazo-4,9-dioxonaphtho[2,3-b]thiophene-3-carboxylate were applied on polyester fibers as disperse dyes and their dyeing properties were studied.     

Furannes et pyrroles disubstitues en 2,3. XVII. Structure des composés formés par eyanuration des halogénométhyl-2 méthoxycarbonyl-3 et −5 furannes

Treatment of methyl 2-bromomethylfuran-3-carboxylate with potassium cyanide yielded methyl 2-cyanomethylfuran-3-carboxylate, methyl 2-methyl-5-cyanofuran-3-carboxylate and two unusual products which appeared by nucleophilic substitution of the activated methylene group of the preceding furylacetonilrile. Products from the cyanide displacement reaction of methyl 5-chloromethylfuran-2-carboxylate are formed in the same way and their previously described formulas are corrected. On the other hand, it was pointed out that phosphorus oxychloride-pentachloride transformation of 2-cyanomethylfuran-3-carboxylic acid leads to 4,6-disubstituted furo[3,2-c]pyridines.     

6-氨基-2-取代吲哚-3-羧酸乙酯及其衍生物的合成与生物活性评价

以2,4-二硝基氯苯和乙酰乙酸乙酯为原料, 经过亲核置换、还原-环化协同反应, 合成了6-氨基-2-甲基吲哚-3-羧酸乙酯, 而后在催化剂作用下, 与乙酰乙酸乙酯反应生成烯胺, 环化合成9-羟基-2,7-二甲基吡咯(2,3-f)喹啉-3-羧酸乙酯; 类似地, 合成了6-氨基-2-苯基吲哚-3-羧酸乙酯和6-氨基-2-(呋喃-2'-基)吲哚-3-羧酸乙酯. 其结构均由¹H NMR, IR以及MS波谱数据表征. 所得化合物具有抑制肺癌A549细胞生长的活性, 其抑制效果具有浓度依赖性.     

Synthesis of the 2,3,4-trisubstituted indole fragments of nosiheptide and glycothiohexide

Two routes to the protected 4-hydroxymethyl-3-methylindole-2-carboxylate fragment 17 of the thiopeptide antibiotic nosiheptide are described starting from methyl 4-methylindole-2-carboxylate 11, itself prepared in two steps, or from 3-amino-4-chlorobenzoic acid 26. The first route can be adapted to the synthesis of a fragment of the related antibiotic glycothiohexide-alpha, the 3,4-bis(hydroxymethyl)indole-2-carboxylate in which the two hydroxymethyl groups are differentiated as in indole 19 or the lactone 20.     

Über den isomerisierungsmechanismus phenylsubstituierter cyclopropene

The thermal and thermocatalytic isomerisations of methyl 2,3,3-triphenylcyclopropene-1-carboxylate to methyl 2,3-diphenylindene-1-carboxylate have been studied. The rate constants of cyclopropene ring opening were determined and parameters of activation were calculated for the thermal process. The formation of cyclopropene and indene derivatives under the photochemical decomposition of methyl 3,3,5-triphenylpyrazolenine-4-carboxylate is discussed.     

Synthesis and selected reactions of ethyl 5-(1-chloroethyl)-2-methylfuran-3-carboxylate

Ethyl 2-methylfuran-3-carboxylate is smoothly chloroethylated at 0°C in the 5 position of the ring. The resulting halide alkylates secondary amines but eliminates HCl with sodium diethyl phosphite under the Michaelis-Becker reaction conditions and with trimethyl phosphite under the Arbuzov reaction conditions. In the reaction with sodium diethyl phosphite, small amounts of 5-[1-(diethoxyphosphoryl)ethyl]furan-3-carboxylate and 5-ethylfuran-3-carboxylate are formed. In the Arbuzov reaction at a 1: 1.22 furan: trimethyl phosphite molar ratio, methyl 2,4-dimethyl-1-methoxy-1-oxo-1λ⁵-1,2-dihydrophospheto[3,2-b]furan-5-carboxylate was isolated.     

A novel king closure and a new synthesis of 3-deazaguanine

The reaction of methyl 5(4)-cyanomethylimidazole-4(5)-carboxylate with hydroxylamine provided methyl 5(4)-carboxamidoximylmethylimidazole-4(5)-carboxylate which cyclized on reduction Lo yield 3-deazaguanine.     

Alkylation of quindoline and quindoline-11-carboxylic acid

The reaction between quindoline-11-carboxylic acid and alcohols in acid media gives the quindoline-11-carboxylate esters, but quindoline-11-carboxylic acid or its hydrochloride react with haloalkanes in the presence of basic catalysts and water binders to give 10-alkylquindoline-11-carboxylate esters. 10-Alkylquindolines were obtained similarly. Alkylation of 1-alkylquindoline-11-carboxylate esters in neutral media affords the quaternary salts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1375–1379, October, 1986.