Synthesis and NMR elucidation of novel penta‐cycloundecane amine derivatives as potential antituberculosis agents

Abstract

The synthesis and NMR elucidation of five novel penta-cycloundecane amine derivatives are reported. These compounds are potential antituberculosis agents. The (1)H and (13)C spectra showed major overlapping of methine signals of the cage skeleton making it extremely difficult to elucidate these compounds. The overlapping occurs as a result of the additions made to the carbonyl carbon (C-8/C-11) of the cage. The two-dimensional NMR technique proved to be a useful tool in overcoming this problem. All compounds reported are meso compounds thereby not only simplifying the NMR structure elucidation, but also making it indeed possible.

Synthesis and NMR assignment of pentacycloundecane precursors of potential pharmaceutical agents

“…Thus for compound 1, the cis-amide proton (δ = 7.33 ppm) to the carboxamide oxygen appears at a higher frequency compared to the trans-amide proton (δ = 7.08 ppm) due to a through-space deshielding effect of the cis-proton. [24,27] A similar observation was noted in the elucidation of compound 2.…”

Synthesis and NMR elucidation of novel pentacycloundecane‐based peptides

“…One would therefore expect a 3 J ‐coupling constant of about 2–3 Hz according to the Karplus relationship 33. However, in all our previous NMR studies5–11, 14, 28, 34 of the PCU skeleton, this fine coupling constant is never observed. The 1 H NMR spectrum of the peptide 2 (Fig.…”

“…Our group has reported NMR studies of pentacycloundecane (PCU)‐based compounds in a bid to understand how the ‘cage’ skeleton relates to its side ‘arms’ (Fig 1). 5–11 As part of our studies to utilise NMR spectroscopy in the elucidation of PCU derivatives, the synthesis and NMR evaluation of two PCU peptides are reported herein.…”

NMR elucidation of novel SQ109 derivatives

“…NMR and computational study of 'cage' molecules such as pentacycloundecane and trishomocubane based compounds has been a major focus of our group for the past 5 years [25][26][27][28][29][30][31][32][33][34][35][36]. We recently reported the NMR elucidation of pentacycloundecane based tetraamines [37,38] which were screened for their anti-tuberculosis activities [39]. Herein we report full NMR studies of SQ109 and analogues (2-6) (Fig.…”