... were recorded on a Nicolet Impact 410 instrument as KBr disks.1H NMR spec- tra were recorded on a Bruker Avance DPX-300/500 MHz instrument in CDCl3, chemical shifts (δ ... [6] Granik, VG; Kadushkin, AV Adv Heterocyclic Chem 1999 ... Heteroatom Chemistry DOI 10.1002/hc