1.3- Dimethyl-5-azauracil

By a more detailed study of the reaction of 5-azauracil with diazo-methane it was found that this reaction is considerably accelerated by the presence of a small amount of water, methanol, or dimethyl-formamide. It does not proceed appreciably in absolute ether. By... 

The alkylation of 6-azauracil will be treated later. The first, but not exactly identified dimethyl derivative was prepared by Grundmann." The course of alkylation was studied in greater detail by Gut et al. These authors found that in aqueous alkaline solution and on using alkyl halides or dialkyl sulfates, the main alkylation product is the 1,3-dialkyl derivative (64). Since, however, the alkylation is to some... 

During methylation of 6-azauracil with a theoretical amount of diazomcthane, the 3-methyl derivative (63) was obtained in very good yield. Excess reagent produces the dimethyl derivative (64). During none of the alkylation reactions was it possible to observe the formation of 0-alkyl derivatives of 6-azauracil. This can be taken as evidence that 6-azauracil does not react in the lactim form (e.g., Section II,B, b). 

As mentioned in chapter 4.2.3, aliphatic imines are photochemically rather unreactive. When the C—N double bond is conjugated to an electron withdrawing group (e.g. carbonyl group), as in O-alkyl derivatives of succinimide and phthalimide, the reactivity increases and azetidines are obtained in cycloadditions to olefins486). A somehow similar example is the photoaddition of a 6-azauracil derivative to 2,3-dimethyl-2-butene... 

Dwarfing Succinic acid 2,2-dimethyl hydrazide (daminozide) T rifluormethanesulfonanilides 6-Azauracil Maleic hydrazide... 

The precise requirements for the successful cycloaddition of alkenes to the carbon-nitrogen double bond remain uncertain, although various explanations have been advanced to account for the observed lack of reactivity.130 1,3-Di-methyl-6-azauracil and l,3-dimethyl-6-azathymine, however, undergo high-yield cycloaddition to a variety of alkenes including ethylene, tetramethylethylene, isobutylene, ethyl vinyl ether, vinyl acetate, and isopropenyl acetate. With ethyl vinyl ether and l,3-dimethyl-6-azauracil (160), for example, epimeric azetidines... 

Treatment of 5-substituted 1,3-dimethyluracils (234) with base and an acetamide gives pyridine-2,6-diones (235) ° l,3-dimethyl-5-azauracil (236) undergoes the same type of rearrangement, giving the 5-substituted uracils (237) (Scheme 93). ... 

Palladium-catalyzed cross-coupling of 1,3-dimethyl-5-bromo-6-azauracil 154 with organozinc compounds CF2=CFZnI or CF3C(ZnBr)=CF2 enables one to incorporate these fluorinated alkenyl and alkyl fragments into the 1,2,4-triazine ring and to obtain compounds 155-157 (Scheme 86) <2004MC63>. 

Azauracil and dimethylformamide diethyl acetal refluxed 19 hrs. in chloroform l,3-diethyl-6-azauracil. Y 71%. F. e. s. J. Zemlicka, Coll. 35, 3572 (1970) reaction of dimethylformamide dimethyl acetal with acidic compds. s. J. Gloede and B. Costisella, J. pr. 313, 277 (1971). 

Durr G (1967) l,3-dimethyl-5-fluoro-6-azauradl and some 5-bromo-6-azauracil derivatives. J Med Chem 10 288-289... 

---