NMR-STUDIES OF 4(3H)-QUINAZOLINONES AND 4(3H)-QUINAZOLINETHIONES

Unambiguous H-1 and C-13 NMR assignments for 4(3H)-quinazolinones 1-6 and their corresponding 4-thiones 7-12 have been made. This resulted in the revision of the previous assignments for the two benzenoid carbons (C-5 and C-8) of quinazolinones 1,2,4, and 5. Thionation of the nucleophilic amides 1-6 has been found to cause a distinct change in the C-13 chemical shift of particularly C-4, but also of those of C-4a, C-5, and C-8a. One-bond and several long range heteronuclear coupling constants for the compounds have also been measured.