Barbituric acids isocyanates

R = Me, Ph) to phenyl isocyanate leads to 5-phenylcarbamoyl barbituric acids (87).229 Similarly, the 2-thio compounds are formed in the reaction with... 

As for six-membered heterocycles, barbituric acid derivatives (67) undergo cleavage of the C-4-C-5 bond, giving an isocyanate (68) (spectroscopically identified in the solid state) (Jochym et al., 1988) and products resulting from it, such as ureides or urethanes via addition of external (Barton et al., 1982) or internal (as with... 

This reaction has been modified from acid-catalyzed cyclization of uredo acids from palladium catalyzed MCR among aldehydes, carbon monoxide, and ureas and from Ugi five-component condensation. Alternatively, hydantoins can also be synthesized via other methods, such as the 1,3-Dipolar Cycloaddition of l-oxa-4-azabutadiene and aryl isocyanates and the decomposition of barbituric acids in alcohol. ... 

Dimethylformamide dimethyl acetal has been used as a methine group source for various heteroring closures, particularly for an efficient 2-step indole synthesis from nitro compounds . The investigation of 3H-1,4-benzodiazepines with their two imino functions, particularly one with an a-iminonitrile function, has been added to the highly versatile chemistry of these heterocyclics Barbituric acid and 2,3,5-trioxopyrrolidine derivatives have been obtained through easy base-catalyzed reactions of active methylene compounds with isocyanates From the neighboring biochemical area come these contributions in preparative enzyme chemistry a-Chymotrypsin as well as citrus... 

Only a few workers have reported photochemical reactions of barbiturates. Otsuji et al. found that hydrolysis of 5,5-diethylbarbituric acid, in alkaline solution, is accelerated by UV (254 nm) light.378 Investigations of 5,5-dialkylbarbituric acid photolysis, carried out by Bojarski and coworkers,379,380 questioned a previous photohydrolytic mechanism378 and implicated the photochemical ring-opening reaction within the malonyl moiety with the isocyanate derivative 135 as an intermediate379 (Scheme 12). 

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