2-heteroaralkynyl derivatives of NECA were synthesized and studied in binding and functional assays to assess their potency for the A2a compared to A1adenosine receptors. Compounds bearing an aromatic or heteroaromatic ring, conjugated to the triple bond, showed generally weaker activity at the A2a receptor and lower selectivity (A2a vs A1) than the alkylakynyl derivatives previously reported. However,