Isatins reactions

Isatin, reaction with chloropyruvic add to yield 3-hydroxydnchoninic acid, 40, 55... 

Isatins, reactions with aryloxymagnesium bromides 608-610 o-Isoaniline 299... 

Lactim ethers and thioethers (300) furnish condensed quinazolones 301 when interacted with IA. ° Ring opening of lA s to the corresponding anthranilic acids and reaction of its potassium salts with chloroacetone yields 2-indolyl ketones 302. ° Potassium cyanide with iV-substituted lA s produces iminoindolinones 303, which were readily hydrolyzed to the corresponding isatins. Reaction of 303 to the spiroindoloquinazoline 304 takes place when KCN is treated with excess lA (Scheme 48). When... 

PUtzing erReaction. Quinoline-4-carboxyhc acids are easily prepared by the condensation of isatin [91-56-5] (16) with carbonyl compounds (50). The products may be decarboxylated to the corresponding quinolines. The reaction of isatin with cycHc ketones has been reported, eg, the addition of cyclohexanone gives the tricycHc intermediate (17) [38186-54-8] which upon oxidation produces quinoline-2,3,4-tricarboxyhc acid [16880-83-4] (51). 

The procedure described for the preparation of 3-hydroxycin-choninic acid is adapted from that reported. This synthesis is successful when bromopyruvic acid or its ethyl ester is substituted for chloropyruvic acid. The reaction of isatin with chloropyruvic acid to produce 3-hydroxycinchoninic acid has been reported however, no details or physical properties were given. This method offers a decided advantage over the method involving diazotization of the difficultly accessible 3-aminocinchoninic acid. ... 

Properties.—Mobile, colourless liquid m. p. 5 4 b. p. So 4 sp. gr. o 874 at 20°. Coal-tar benzene usually contains a little thiophene, C4H4S, which may be detected by dissolving a few crystals of isatin (see p. 229) in concentrated sulphuiicacid and shaking up with the benzene. If thiophene is present, a blue colour is produced (indophenin reaction). 

The Doebner reaction can provide the 4-carboxyl quinoline when the Pfitzinger reaction does not." Pfiztinger reaction of pinnacolone with isatin did not provide the desired quinoline. Doebner reaction of aniline with acetaldehyde and pyruvic acid did furnish the quinoline, albeit in only 8% yield. 

The Pfitzinger reaction describes the condensation of an o-aminophenylglyoxylic acid 16 (which can be generated in situ from an isatin IS) with 2 results in a quinoline-4-carboxylic acid (17), which is the subject of its own chapter in this book. ... 

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. " ... 

A mixture of 60 g (0.408 mol) of isatin, 200 mL of 34% potassium hydroxide in diluted alcohol solution, 88 g (1.22 mol) of ethyl methyl ketone and 375 mL of water were stirred and heated under reflux for 72 hours. About 125 mL of liquid was removed by distillation the residue was made slightly acidic and filtered. The filtrate was made strongly acidic to precipitate the reaction product, which was collected by filtration, washed, dried, weighed 70 g (85% yield). 

The Pfitzinger reaction consisting in the alkaline condensation of isatin or 6-bromoisatin with ketones has been applied extensively by Buu-Hoi et af.211.279.310.316,525,553 Cagniant, to acetylthio-... 

Thianaphtheneqiiinone - (109) and diazomethane give a different reaction from that found with isatin, A -methylisatin and coumarandione. In as far as crystalline products could be isolated, the ring expansion occurs here between the sulfur and the carbonyl group in the 2-position. Depending on the solvent, there are formed 3-hydroxy-thiochromone (110), its 0-methyl derivative (111), or (presumably by attack on the 3-keto group of the tautomeric 3,4-diketo form of 110), 3,3 -epoxy-3-methylthiochromone (108). 

The difference in the reaction course for thianaphthenequinone can be explained in the following way in isatin and coumarandione the carbonyl group in the 3-position is considerably more reactive than... 

Reaction of o-toluidine with chloral hydrate in presence of hydroxylamine hydrochloride and subsequent treatment with H2SO4 gave the isatin derivative 337. Bromination of 337 followed by reaction with sodium diethyl malonate gave 338. Catalytic reduction with Pd/C gave the oxoindole derivative 339 that upon hydrolysis with aqueous NaOH followed by... 

The reaction of isatin with tetraphosphorus decasulfidc gives a low yield of compound 1, whose structure was confirmed by X-ray analysis.415... 

Naphtho[2,l-6]furo[2,3-c][l,2,4]triazines 198 were prepared (88JHC-1117) by the reaction of 4-5-benzocoumaran-2,3-dione with thiosemicar-bazide to give 195, whose ethylation in the presence of sodium hydroxide gave 197 via 196. Reaction of 197 with aniline gave 198 via the first displacement of the ethylthio group whose product could be isolated with a shorter reaction time. On the other hand, the similar sequence of reactions on coumaran-2,3-diones differs markedly from that of 4,5-benzocoumaran-2,3-diones, where the cyclization of 195 to 198 could not be effected. The behavior of the later dione resembles that of isatin and thianaphthenequinone (Scheme 41). 

Homoenolate Reactivity The ability to generate homoenolates from enals and its application to the preparation of y-butyrolactones 30, through reaction with an aldehyde or aryl trifluoromethyl ketone, was reported independently by Glorius [8], and Bode and Burstein [9] (Scheme 12.4). A sterically demanding NHC catalyst is required to promote reactivity at the d terminus and to prevent competitive benzoin dimerisation. Nair and co-workers have reported a similar spiro-y-lactone formation reaction using cyclic 1,2-diones, including cyclohexane-1,2-dione and substituted isatin derivatives [10]. 

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