A synthesis of phosphorylated dioxohexahydropyrimidines from N,N'-dimethylurea, activated acetylenes, and trialkyl phosphites.

An efficient synthesis of alkyl 5-(dialkoxy- phosphoryl)-1,3-dimethyl-2, 6-dioxo-hexahydropyrimidine-4-carboxylates is described. This involves the reaction of N,N'-dimethylurea and dialkyl acetylendicarboxylates in the presence of trialkyl phosphites. Under similar conditions, triphenyl phosphite led to alkyl 5-(diphenoxyphosphoryl)-1,3-dimethyl-2,6-dioxo-hexahydro-4-pyrimidinecarboxylates.