6- -quinoline, reaction with dimedones

The analogous reaction to that described in Equation (42) using paraformaldehyde in equimolar amount to dimedone (instead of a large excess) was irradiated for 3 min to yield pyrimido[4,5- ]quinoline-4,6-dione 591 via formation of intermediate adduct 590 <2006TL27>. The 5-aryl-5,6,7,8,9,10-hexahydropyrimido[4,5-/ ]quinolines 592 were also prepared by the cyclocondensation reaction of 6-aminopyrimidine 460 with dimedone and 4-sub-stituted benzaldehydes by boiling in absolute ethanol for 30 min <1998JHC231>. 

The adduct 2-(4,4-dimethyl-2,6-dioxocyclohexyl)-4-oxo-4-phenylbu-tanoic acid 261 was obtained from the reaction of dimedone and / -benzoylacrylic acid, which upon reaction with ammonium acetate in acetic acid led to the pyridine ring that accompanied by decarboxylation to give 262. When the reaction was done in the presence of methylamine, benzylamine, or p-toluidine, it gave quinolines 263 whose oxidation by chromic acid in pyridine gave 264 (01CHE1111) (Scheme 48). 

The addition of water (see Section II,B) and other nucleophiles across the 3,4-double bond of quinazoline is well established.1,2 More recently other nucleophiles, such as dimedone, have given isolable 3,4-adducts.110 Similarly, malononitrile and other compounds with active methylene groups added across the 3,4-double bond of quinazoline, but in this case the reaction proceeded further with ring opening and formation of 2-amino-3-cyano-quinoline.110111 The dimedone adduct was also made to react further in the presence of alkali to form the acridone 38.110... 

Reactions of 6-aminouracils with various 2-substituted cyclohexanones such as the aldehyde (264) give reduced pyrimido[4,5-f ]quinolines (265) (57BRP774095, 58JA3449), and other cyclohexanone derivatives used include the 2-dimethylaminomethyl (Mannich) bases (78AP542) and the 5-benzylidenedimedones (266) formed in situ from dimedone and aldehydes (67KGS395, cf. 67KGS406). 

The octahydroquinolines 24 and decahydroacridines were obtained from dimedone. On montmorillonite KSF clay, acridine derivatives 25 were obtained. Reaction of arylidenemalononitriles with cyclic ketones gave 2-amino-3-cyanopyridines 26. Reaction of diphenylamine and dicarboxylic acids or arylacetic acids was catalyzed by zinc chloride to give acridines. Pyrimido[4,5-Z>]quinolines 27 were synthesized. ... 

General procedure for the synthesis of 1,4,7,8-tetrahydro-2,7,7-trimethyl-4-aryl-5(6H)-oxo-quinolin-3-carboxylic acid alkyl ester (5). A mixture of aldehyde (1 2 mmol), dimedone (2 2 mmol), p-ketoester (3 2 mmol), and ammonium acetate (4 3 mmol) was thoroughly mixed in a mortar followed by grinding till the completion of reaction as indicated by TLC (12-45 min). The resultant mass was washed with water to remove any unreacted ammonium acetate and was air-dried to give a crude product which on recrystallization from ethanol afforded the pure desired compound (5) in excellent yield (80-95%). 

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