The reactions of ureas with glyoxylic acid and methyl glyoxylate

The reactions of urea, methylurea and dimethylureas with glyoxylic acid and its methyl ester to give α-substituted hydantoic acid derivatives ( 4 , 5 , 6 , 7 ) and substituted allantoic acid derivatives ( 8 ) is discussed. The cyclization of the hydantoates and allantoates to 5-substituted hydantoins ( 11 , 12 ) is also described.