P. R. Golubev, A. S. Pankova, M. A. Kuznetsov
“Transition-Metal-Free Approach to 4-Ethynylpyrimidines via Alkenynones”
Eur. J. Org. Chem. 2014, 3614-3621
A practical approach to the synthesis of 4-ethynylpyrimidines by the condensation of arylamidines with 2-aryl-1-ethoxy-5-(trimethylsilyl)pent-1-en-4-yn-3-ones has been developed. As these latter ketones are easily accessible from bis(trimethylsilyl)acetylene and arylacetyl chlorides, the regioselective condensation reported herein provides a facile access to both TMS-protected and unprotected 4-ethynylpyrimidines in yields of up to 85%.