Radicals substituted by hetero atoms or by carbon atoms having three bonds

Official title: Radicals substituted by hetero atoms or by carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. an ester or nitrile radical

C07D503/16 (Radicals substituted by hetero atoms or by carbon atoms having three bonds) appears on 2 US grants and 4 published applications in this corpus.