The First Selenium Isologues of 2-Pyrones and Coumarins: Synthesis, Structures, and Reactions

The reactions of 2-pyrones and coumarins with hydrochlorosilane, elemental selenium, and 4-dimethylaminopyridine (DMAP) gave 2-selenopyrones and selenocoumarins in moderate to good yields. Their formation was disclosed by X-ray molecular structure analyses. The NMR and UV-vis spectra of these products were highly similar, except for (SeNMR)-Se-77 spectra which were observed in the range from 649 to 984 ppm. Methylation of 2-selenopyrones gave 2-methylselenopyrylium salts in high yields.