Syntheses of folic acid models, 6‐( N ‐acylarylamino)methyllumazines

Folic acid models, 1,3‐dimethyl‐6‐( N ‐acylarylamino)methyllumazines 9 , were synthesized from 6‐bromomethyl‐1,3‐dimethyllumazine ( 6 ), which was derived from 5,6‐diamino‐1,3‐dimethyluracil ( 1 ) by the condensation with 1,3‐dihydroxyacetone, followed by bromination. The bromide 6 was also prepared by the cycloaddition between 3,6,8‐trioxo‐5,7‐dimethyl‐5,6,7,8‐tetrahydro‐3H‐pyrimido[5,4‐ c ][1,2,5]oxadiazine ( 4 ) and 1‐propenyl trimethylsilyl ether followed by bromination. The folic acid models 9 were also directly synthesized from the oxadiazine 4 and 3‐( N ‐acylaryl)amino‐1‐propenyl trimethylsilyl ether 8 by cycloaddition.