1,720,997 research outputs found
A New Efficient Route to Imidazo[4,5-c]pyrazol-5-ones
No full textThe synthesis of imidazo[4,5-c]pyrazol-5-ones (6) is reported. 5-Amino-4-ethoxycarbonylaminopyrazoles 3a-g when heated at 200°for 2 hours afford 6a-g. In a similar manner imidazo[4,5-c]pyrazol-5-one (6a) is readily obtained from 4-amino-5-ethoxycarbonylaminopyrazole (5a)
STRUCTURES OF E,E-3-(PARA-TOLYLIMINO)-2-BUTANONE OXIME AND E,Z-4-(PARA-TOLYLIMINO)-2,3-PENTANEDIONE 3-OXIME - AN X-RAY CRYSTALLOGRAPHIC INVESTIGATION ON BONDING IN OXIMES
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An X‐ray crystallographic study on the geometry of the C‐‐O group and the [1,5] sigmatropic rearrangement from C‐nitroso compounds to oximes
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Synthesis of 4-(Pyrazol-5-yl)-1,2,4-triazole-3-thiones
No full textCondensation of pyrazolyl isothiocyanates 2 with N-substituted hydrazines provided the 2-methyl/phenyl-4-(pyrazol-5-yl)thiosemicarbazides 3. Cyclization of 3 with formic acid-acetic anhydride or with triethyl orthoacetate-acetic anhydride provided 4-(pyrazol-5-yl)-1,2,4-triazole-3- thiones 4a-f and 5-methyl-4-(pyrazol-5-yl)-1,2,4-triazole-3-thiones 4g-l respectively
A synthetic entry to 1- and 2-aminopyrazolo[3,4-d]-1,2,3-triazoles
No full text2-Aminopyrazolo[3,4-d]-1,2,3-triazole (4) and 1-aminopyrazolo[3,4-d]-1,2,3-triazole (5) were prepared by direct amination of pyrazolo[3,4-d]-1,2,3-triazole with hydroxylamine O-sulphonic acid in aqueous potassium hydroxide. The ratio of 4 to 5 was 2:3. © 1995
Sintesi di (±)-2-azetidinoni da beta-enamminochetoesteri
No full textIl nucleo 2-azetidinonico (beta-lattamico) rappresenta l'unità strutturale comune ad un gran numero di composti biologicamente attivi, tra cui penicilline e cefalosporine. L'importanza farmacologica degli antibiotici beta-lattamici e la crescente richiesta di farmaci aventi una più elevata stabilità chimica e metabolica rendono ancora particolarmente attraente lo sviluppo di nuove metodologie per l'ottenimento del nucleo beta-lattamico in maniera semplice e stereoselettiva.
Il nostro contributo in questo campo si è concretizzato nella sintesi diastereoselettiva di 3-(1-idrossietil)-2-azetidinoni protetti, strutturalmente correlati alla tienamicina, in forma racemica. Il passaggio chiave è rappresentato dalla reazione di ciclizzazione di opportuni beta-ammino esteri che si ottengono per elaborazione di beta-enamminochetoesteri, facilmente ottenuti per reazione del metil acetoacetato con alchil cianoformiati in presenza di quantità catalitiche di [Zn(acac)2
Synthesis of 5,7-dimethylpyrazolo[3',4':4,5]thiazolo-[2,3-c]-1,2,4-triazole, an analogue of tricyclazole
No full textAn efficient synthesis of 5,7-dimethylpyrazolo[3',4':4,5]thiazolo-[2,3- c]-1,2,4-triazole (2), an analogue of tricyclazole, was achieved by treatment of 4-(4'-amino-1',3'-dimethylpyrazol-5'-yl)-1,2,4-triazole-3-thione (7) with sodium nitrite in acidic medium followed by irradiation with UV light
Imidazo[4,5-c]pyrazoles Synthesis of 4-,5- and 6-Substituted Derivatives
No full textThe syntheses of 4-, 5-, and 6-substituted imidazo[4,5-c]pyrazoles, compounds of potential biological activity, are reported. Copyright © 1996 Published by Elsevier Science Ltd
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