Isatic acid, isatin

The Pfitzinger reaction entails the synthesis of quinoline-4-carboxylic acids 2 via condensation of isatic acids formed from isatins 1 and a-methylene carbonyl compounds in the presence of strong aqueous bases. Subsequent decarboxylation can afford the corresponding quinolines. " ... 

In 1886 Pfltzinger reported a formal extension of the known Friedlander protocol for the synthesis of quinolic acids. This new protocol relied on the use of isatin which is much more stable than the ort/io-aminoaryl intermediates that are required in the Friedlander quinoline synthesis. In this early paper, Pfitzinger reports that upon heating of isatin 3 in the presence of aqueous sodium hydroxide, the former is. hydrolyzed to the isatic acid 4 which then in the presence of acetone reacts to give aniluvitonic acid 6. ... 

Different reaction pathways can be observed in the reaction of isatins with carbanions under photochemical or thermal conditions. Thus, the reaction of isatin and isoxazolone under thermal conditions led to addition at position C-3, whilst under UV irradiation cleavage of the isatinic N1-C2 bond occured yielding isatic acid, which subsequently condensed with isoxazolone446 (Scheme 106). 

Anthroxanic acid can be reduced (FeS04/NH3) to isatic acid (156), which then recyclizes to isatin (157).189,183 3-Acylanthranils on reduction (Zn/HOAc or H2/Raney Ni) form indoxyls, also by re-cyclization.236... 

SYNS o-AMINOBENZOYLFORMIC ANHYDRIDE 2,3-DIKETOINDOLINE 2,3-DIOXOINDOLINE 2,3-INDOLINEDIONE ISATIC ACID LACTAXI ISATIN... 

IRRATHENE R see PJS750 IRTRAN 1 see MAF500 IRTRAN 3 see CASOOO 2341 1.S. see BIQ500 ISACONITINE see PIC250 ISATIC ACID LACTAM see ICROOO ISATIDINE see RFUOOO ISATIN see ICROOO... 

Claisen and Shadwell discovered a new synthetical method for production of isatin in 1879. By action of silver cyanide on orthonitrobenzoyl chloride, orthonitrobenzoyl cyanide is produced, and this is converted into orthonitrophenylglyoxylie acid by saponification and subsequent treatment with an alkali. On reduction of this acid in alkaline solution, a salt of isatic acid (orthoamidophenylglyoxylic acid) is produced, from which isatin may be separated by an acid. 

Claisen and Shadwell proved that isatic acid is orthoamidophenylglyoxylic acid, and that isatin is its inner anhydride by a direct synthesis [26]. However, various properties of isatin noted by Baeyer speak for the presence of an hydroxyl group according to the formula ... 

Kolbe discovered nitroethane, C2H6NO2, independently of Victor Meyer (see p. 808). His last research, on isatic acid (indigotic acid) formed by the oxidation of isatin, was published in the year of his death. ... 

Baeyer and Caro obtained indole by passing the vapour of ethylaniline through a red-hot tube, and also synthesised it from diethyl o-toluidine. Indole was prepared from isatic acid (o-NH2 C6H4 CO C02H) by Baeyer s pupil W. Suida and isatin synthesised from o-nitrobenzoic acid by Claisen and J. ShadwelL ... 

Isatic Acid o-Aminobenzoylformic acid, o-aminophenylglyoxylic add, isatinic acid) CO-COOH... 

In a catalyst-free, aqueous-mediated MCR facilitated by sonication, isat-ins 200, 5-amino-3-methylpyrazole 201 and a-mercaptoacetic acids 202 reacted to form spiro(indole-3,4 -pyrazolo[3,4-e][l,4]thiazepines) 203 in high yield. Replacement of the isatin with acenaphthylene-1,2-dione or N-substitued piperidin-4-ones gave the corresponding spiro(pyrazolo-1,4-thiazepines) (13RA18992). 

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