反应详情

boiling an aqueous solution of glycine and urea in a molar ratio of 1:1.8 to 1:5 to form hydantoic acid as an intermediate, and directly cyclizing the hydantoic acid intermediate by adding to the solution concentrated sulfuric acid in a molar ratio of 1:0.3 to 1:1 relative to the glycine to form hydantoin of the Formula (I) as a precipitate and a mother liquor: ##STR8## and separating the precipitate of hydantoin from the mother liquor; (b) condensing the hydantoin formed during step (a) with an aromatic aldehyde of the Formula (II) ##STR9## in an aqueous solution in the presence of ethanolamine or morpholine to obtain a 5-arylidene-methyl-hydantoin of the Formula (III) ##STR10## (c) quantitatively reducing the compound of the Formula (III) prepared in step (b) in a diluted alkaline medium in the presence of a Raney nickel or palladium-on-charcoal catalyst, to obtain a 5-aryl-methyl-hydantoin of the Formula (IV) ##STR11## and; (d) subjecting the compound of the Formula (IV) to alkaline hydrolysis to yield the compound of the Formula (V).