Transition‐Metal‐Free Approach to 4‐Ethynylpyrimidines via Alkenynones

Abstract

Abstract 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 %.