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Compounds with bridgehead nitrogen 66 —NMR spectra and stereochemistry of derivatives of 1,2,3,4,6,7,12,12b‐ octahydropyrimido [1′, 6′:1,2] pyrido [3,4‐ b ]indol‐2‐one and of 1,3,4,6,7,11b‐hexahydropyrimido [6,1‐ a ] isoquinolin‐2‐one
Author(s) -
Crabb Trevor A.,
Patel Asmita V.
Publication year - 1991
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260291012
Subject(s) - chemistry , conformational isomerism , isoquinoline , stereochemistry , nmr spectra database , nitrogen , nuclear magnetic resonance spectroscopy , spectral line , molecule , organic chemistry , physics , astronomy
Comparison of the NMR spectra of 3‐methyl‐1,2,3,4,6,7,12,12b‐octahydropyrimido [1′,6′ : 1,2]pyrido[3,4‐ b ] indol‐2‐one and of cis ‐(H‐6, H‐12b)‐3,6‐dimethyl‐ 1,2,3,4,6,7,12,12b‐octahydropyrimido [1′,6′:1,2]pyrido[3,4‐ b ] indol‐2‐one shows the former to exist in solution at 25°C as an equilibrium mixture containing ca. 20% N ‐inside‐ cis ‐ and ca. 80% trans ‐fused conformers, and the latter to adopt exclusively the trans ‐fused conformer. The related 3‐methyl‐ 1,3,4,6,7,11b‐ hexahydropyrimido [6,1‐ a ] isoquinoline‐2‐one adopts a ca. 53% trans ‐fused 47% cis ‐fused equilibrium.