Choua C Vu, D. Walker, Jason Wells
Jul 1, 2002
Citations
0
Influential Citations
14
Citations
Journal
Journal of Heterocyclic Chemistry
Abstract
The known 1,8-naphthyridine-2,7-dicarboxaldehyde was prepared by SeO2 oxidation of 2,7-dimethyl-1,8-naphthyridine. The dimethylated naphthyridine molecule was assembled from an adaptation of the Skraup synthesis using 2-amino-6-methylpyridine and crotonaldehyde to afford a reproducible 37% yield, and constitute a significant advance over the literature of this reaction. The condensation of 1,8-naph-thyridine-2,7-dicarboxaldehyde with various primary amines (R = -C6H11, -CH2C6H5, -C(CH3)3, -C10H15, and CH2CH2SCH2CH3) in alcohol affords diimines 1(a-e). The inherent crystallinity of 1(a-e) affords pure compounds in reasonable to excellent yields (ca. 70%) after evaporation of solvent and recrystallization. The anticipated spectroscopic features of (N=C-H) 1H nmr shift and v(C=N) in the ir spectrum appear around 8.50 δ and 1640 cm−1, respectively, for the series 1(a-e). These novel naph-thyridines typically display the signature 1H nmr doublets at ca. 8.15-8.30 δ ascribed to the 3 and 4 naphthyridine protons, consistent with a mirror plane (through the quaternary carbons) perpendicular to the naphthyridine plane, and syn, syn relationships of the naphthyridine moiety with each imine nitrogen lone pair. Complexation studies of 1(a-e) with transition metals of biological relevance such as copper(I) and copper(II) will be reported elsewhere.