K2CO3-mediated, direct C-H bond selenation and thiolation of 1,3,4-oxadiazoles in the absence of metal catalyst: an eco-friendly approach Rafique, Jamal ; Saba, Sumbal ; Rosário, Alisson R. ; Zeni, Gilson ; Braga, Antonio L. Abstract Publication: RSC Advances Pub Date: 2014 DOI: 10.1039/C4RA10490K Bibcode: 2014RSCAd...451648R