Straightforward Pyrimidine Ring Construction: A Versatile Tool for the Synthesis of Nucleobase and Nucleoside Analogues.

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 of a 1-substituted pyrimidine library that includes nucleoside analogues. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)