Two-step conversion of 3,4,4,5-tetrachloro-4H-1,2,6-thiadiazine into 4,5,6-trichloropyrimidine-2-carbonitrile

Catalyzed Methods to Synthesize Pyrimidine and Related Heterocyclic Compounds

This review covers articles published in the period from 2010 to mid-2022 on synthetic advances in the formation of pyrimidine and related heterocyclic compounds. Special emphasis has been given to the different types of cycloadditions, taking into account the number of their components and leading to the formation of the pyrimidine ring. Due to the large number of publications on the Biginelli reaction and related reactions, this will be dealt with in a separate review in the near future.

4,5,6-Trichloropyrimidine-2-carboxamide

Reaction of 4,5,6-trichloropyrimidine-2-carbonitrile (1) with concentrated sulfuric acid at ca. 20 °C gave 4,5,6-trichloropyrimidine-2-carboxamide (5) in 91% yield. The new compound was fully characterized by IR, MALDI-TOF, NMR and elemental analysis.

Synthesis of 2-Cyanopyrimidines

4,6-Dichloro-2-(methylthio)pyrimidine (7) was converted to 4-chloro-6-methoxy-2-(methylthio)pyrimidine (15) and 4,6-dimethoxy-2-(methylthio)pyrimidine (14). Chlorination of the latter with N-chlorosuccinimide (NCS) affords 5-chloro-4,6-dimethoxy-2-(methylthio)pyrimidine (16) in 56% yield. Both methylthiopyrimidines 15 and 14 were converted in two steps to 4-chloro-6-methoxypyrimidine-2-carbonitrile (13) and 4,6-dimethoxypyrimidine-2-carbonitrile (12), respectively, after oxidation to sulfones and displacement of the sulfinate group with KCN. 4,6-Dimethoxypyrimidine-2-carbonitrile (12) was chlorinated with NCS to give 5-chloro-4,6-dimethoxypyrimidine-2-carbonitrile (10) in 53% yield. All new compounds were fully characterized.