Simple aromatic amines from justicia gendarussa. 13C NMR spectra of the bases and their analogues

Abstract

Four simple 0-disubstituted aromatic amines have been isolated from the leaves of Justicia gendarussa Burm and characterized as 2-amino benzyl alcohol ( 3), 2-(2′-amino-benzylamino) benzyl alcohol ( 4) and their respective 0-methyl ethers 1 and 2 from 1H NMR and mass spectral analyses of the bases and their acetates. Structures 3 and 4 have also been confirmed by synthesis. Intramolecular hydrogen bonding (cf. 9, 13 and 14) has been envisaged to explain the unexpected shielding of -CH 2-OH carbon signals of 3 4 on acetylation and upfield displacement of -CH 2-N signal of 2a vs 4a in their 13C NMR spectra in CDCl 3 solution 1 J CH values have been found to be useful for the assignment of aromatic methine carbon signals in o-disubstituted compounds. Part 68 of the series Studies on Indian medicinal plants. For Part 67, see P. K. Dutta, D. Bagchi and S.C. Pakrashi, Indian J. Chem. in press.