Abstract: NMR spectra of 5 new kinds of α,α'-dioxoketene cyclic N, N-acetals are reported in this paper. The structures. were determined by ¹H、¹³C NMR spectra etc., and the chemical shifts of all NMR peaks kaye been assigned. The effects of structure on the chemical shifts are discussed.

Key words: β-conjugated didetenes, α,α'-dioxoketene cyclic N,N-acetals, ¹H、¹³C NMR spectrum