A Carbon‐13 and nitrogen‐15 NMR study of some nitrogen heterocycles

Abstract

A number of phenyl‐substituted nitrogen heterocycles and the corresponding 2,6‐diethylphenyl derivatives were examined by 13C nmr in order to verify that the heterocyclic ring system was the same in both series. The heterocyclic ring carbon shifts did not differ substantially between the phenyl and 2,6‐diethylphenyl derivatives for all systems except one, where substantial differences were also seen in the 15N chemical shifts. Acetylated derivatives were prepared to confirm the cyclization mode in this latter case.

A hydantoin isoform of cyclic N6-threonylcarbamoyladenosine (ct6A) is present in tRNAs

“…To obtain a signature of the hydantoin isoform of ct 6 A, we further recorded 1 H, 15 N-HSQC and 1 H, 15 N-HMBC spectra for the ct 6 A nucleoside to determine 15 N chemical shifts (Table 2 and Supplementary Figure S11 ). The chemical shifts of N6 (163 ppm) and N11 (87 ppm) of ct 6 A were in the range characteristic to urea-type nitrogens, consistent with the analogous nitrogens in the N 3 -phenyl hydantoin structure ( 38 ), supporting the idea that the hydantoin isoform actually exists in solution. In the case of the oxazolone isoform, the C=N–Ar type nitrogen would appear at much lower magnetic field ( 39 ).…”

Design, synthesis, and biological activity of rigid acetanilide herbicides

“…12 3 (D Based on the demonstrated herbicidal activity of the chloroacetanilides and their presumed mechanism of action as alkylating agents, it was proposed that rigid acetanilides, related to the commercial herbicide Lasso, be prepared and screened for biological activity. The proposed compounds, of general structure 4, represent a series which incorporates a latent leaving group X analogous to the oxonium ion in Buchman and Komoroski (1980) for a 13C NMR analysis.…”