A general route to 1,2,4-trisubstituted pyrimidines is described in one to three steps from a common key precursor, diazadienium iodide 2. An efficient preliminary [4+2] cyclocondensation reaction between the azabutadiene building block 2 and various iso(thio)cyanates constitutes an original construction of the pyrimidine skeleton. Subsequent structural modifications on the heterocycle allow the elaboration
A facile and simple regioselective synthesis of uracils and their thio analogues has been achieved by cyclocondensation of a common precursor, diazadienium iodide 1, and isothiocyanates 2a,b. The key step in this synthetic process is the preparation of 4-methylsulfanylpyrimidine-2-thiones 3a,b, which after further elaboration gave the expected uracil analogues 4a,b-8a,b.
report thiouracil-catalyzed α-selective O-glycosylations employing easily accessible glycosyl trichloroacetimidate donors without using any co-catalyst or additive. A variety of alcohol nucleophiles including saccharides, and amino acids with different protecting groups containing glycosyl trichloroacetimidate donors were successfully α-glycosylated using an operationally simple protocol. Moreover, mechanistic