Synthesis of carbamoylformhydroxymoyl chlorides and study of their reactivities

Carbamoylformhydroxymoyl chlorides were synthesized by the reactions of carbamoylformamide oximes with sodium nitrite in the presence of hydrochloric acid, and their reactivities were examined.     

Trifluoromethylated amino alcohols as chiral ligands for highly enantioselective Reformatsky reaction

The enantioselective Reformatsky reaction of PhCHO was achieved by the use of trifluoromethylated amino alcohols as chiral ligands to afford the corresponding optically active β-hydroxy ester with up to 90% ee.     

铟参与的4-溴-1，1，1-三氟-2-丁烯与α-烷氧基醛亚胺的烯丙化反应：4，4，4-三氟-γ-羟基缬氨酸的合成

铟参与的4-溴-1,1,1-三氟-2-丁烯与α-烷氧基醛亚胺的烯丙化反应以中等的产率和高非对映选择性生成了高烯丙基胺3.从甘油醛亚胺和4-溴-1,1,1-三氟-2-丁烯反应制备的高烯丙基胺3g出发,以7步反应24%的总产率合成了4,4,4-三氟-γ-羟基缬氨酸11.     

Ring-opening and recyclization of 3,4-diacylfuroxans by nitrogen nucleophiles

Interaction of 3,4-diacylfuroxans with hydroxylamine hydrochloride results in the formation of substituted 4,5-bis (hydroximino)-4,5-dihydroisoxazoles, whereas the reaction of 3,4-bis(4-methylfurazanoyl-3)furoxan with hydrazine hydrate in acetic acid affords 3-[4,5-bis(hydroximino)-4,5-dihydro-1H-pyrazol-3-yl]-4-methylfurazan. N-Acyl-, N-nitro-, N-alkyl- and N-adamantyl derivatives of the latter compound have been synthesized. X-Ray structure determinations together with density functional theoretical calculations are reported.     

Reactions of 3-cyclopropyl-3-oxopropionitrile anion generated by electroreduction of 5-cyclopropylisoxazole

3-Cyclopropyl-3-oxopropionitrile anion obtained by cathodic reduction of 5-cyclopropylisoxazole in an aprotic medium was used as an example to demonstrate that cyano ketone anions show a dual reactivity. The reaction of acetyl chloride with the electrogenerated tetrabutylammonium salt of 3-cyclopropyl-3-oxopropionitrile gave O-acylation products, whereas the reaction with its sodium salt gives C-acylation products. The reactions of these salts with hydroxylamine hydrochloride follow a different route: in the case of the tetrabutylammonium salt, resinification takes place, while in the case of the sodium salt, 5-amino-3-cyclopropylisoxazole is formed. The condensation of this product with 4,4,4-trifluoro-1-(2-thienyl)butane-1,3-dione in glacial AcOH affords 3-cyclopropyl-6-(2-thienyl)-4-(trifluoromethyl)isoxazolo[5,4-b]pyridine in 85% yield. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2110–2114, November, 2007.     

New rearrangement of benzo[d]isoxazoles: recyclization of 4-R-6-nitrobenzo[d]isoxazole-3-carbaldehyde arylhydrazones into 2-aryl-4-(2-hydroxy-4-nitro-6-R-phenyl)-1,2,3-triazoles

The previously unknown recyclization of nitrobenzo[d]isoxazoles into 1,2,3-triazoles was found. A general method for the synthesis of 2-aryl-4-(2-hydroxy-4-nitro-6-R-phenyl)-1,2,3-triazoles from 4-R-6-nitrobenzo[d]isoxazole-3-carbaldehyde arylhydrazones was developed.     

Novel Method for Soluble‐Polymer‐Supported Synthesis of 3,4,5‐Trisubstituted Isoxazoles

A practical and efficient liquid‐phase synthesis of 3,4,5‐trisubstituted isoxazoles using poly(ethylene glycol) as supported is described. Soluble‐polymer‐supported nitrile oxide generated in situ reacted with chalcones to afford polymer‐supported isoxazolines, which were cleaved by sodium methoxide to generate 3,4,5‐trisubstituted isoxazoles instead of 3,4,5‐trisubstituted isoxazolines. This sequential process provided a novel method to synthesize 3,4,5‐trisubstituted isoxazoles.     

Ionic Liquid–Mediated One-Pot Synthesis of 5-(Trifluoromethyl)-4,7-dihydrotetrazolo[1,5-a]pyrimidine Derivatives

A facile one-pot synthesis of 5-(trifluoromethyl)-4,7-dihydrotetrazolo[1,5-a]pyrimidine derivatives is described via a three-component reaction of aldehydes with 5-aminotetrazole and ethyl 4,4,4-trifluoro-3-oxobutanoate or 4,4,4-trifluoro-1-phenylbutane-1,3-dione in ionic liquid. This method has the advantages of short synthetic route, operational simplicities, good yields, ecofriendliness, and recyclability of the solvent.     

Silylated β-enaminones as precursors in the regioselective synthesis of silyl pyrazoles

Silyl β-enaminones have been synthesized by reductive cleavage of 5-silyl, 3-, 4- and 5-silylmethylisoxazoles.These versatile synthons bearing different silyl groups in various positions of the enaminoketonic system are of great interest in the regioselective synthesis of 3- or 5-silylpyrazoles and 3-, 4- or 5-silylmethylpyrazoles, which can serve as building blocks in heterocyclic chemistry.     

A facile and convenient synthesis of novel imidazo[1,2-b] isoxazoles and their Mannich bases as potential biodynamic agents

A series of novel imidazo[1,2-b]isoxazoles 3 and their Mannich bases 4–6 were synthesized via convenient reactions. The reaction of 3-aminoisoxazole 1 with substituted phenacyl bromides 2 in dry ethanol afforded the corresponding 6-methyl-3-aryl imidazo[1,2-b]isoxazoles 3 in good yields.Compounds 3 on treatment with 37% formaline and secondary amines furnished the corresponding novel Mannich bases viz., 6-methyl-3-aryl-2-(morpholine/pyrrolidin-1-yl/piperidin-1-yl)-methyl-imidazo[1,2-b]isoxazoles 4–6.