Synthesis of functionalized pyrimidouracils by ruthenium-catalyzed oxidative insertion of (hetero)aryl methanols into N-uracil amidines

A dehydrogenative coupling of N-uracil amidines with (hetero)aryl methanols has been developed, allowing for the facile synthesis of a broad range of structurally diverse pyrimidouracils. By applying [RuCl2(p-cymene)](2)/Cs2CO3 as an efficient catalytic system, the easily available, cheap (hetero)aryl methanols were firstly employed for oxidative insertion/C-H amination into the N-uracil amidines, providing highly functionalized pyrimido[4,5-d]pyrimidine-2,4-diones. Due to the better stability of alcohols than aldehydes, this synthetic protocol is applicable to a broad range of alcoholic substrates and does not required any protection during the whole preparation process. The presented protocol has the potential to prepare valuable products which cannot be accessed presently or extremely arduous to procure by following regular procedure. Hence, this is a remarkably improved protocol compared with the existing methodologies. The overall reaction sequence is an effective oxidation-imination-cyclization tandem process catalyzed by ruthenium catalyst.

Automated summary

A new synthesis method has been developed for the facile synthesis of structurally diverse pyrimidouracils using a dehydrogenative coupling reaction. This method is applicable to a broad range of substrates and has the potential to prepare valuable products that are currently difficult to access. The overall reaction sequence involves an efficient oxidation-imination-cyclization tandem process catalyzed by a ruthenium catalyst.