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NMR spectra and stereochemistry of perhydrooxazolo[3,4-a]pyridines

✍ Scribed by Trevor A. Crabb; Andrew N. Trethewey; Yoshito Takeuchi

Publisher
John Wiley and Sons
Year
1988
Tongue
English
Weight
240 KB
Volume
26
Category
Article
ISSN
0749-1581

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✦ Synopsis

Low-temperature 13C and 'H NMR spectra show perhydrooxazolo[3,4-a]pyridine to exist in CDCI,-CFCI, solution at 183 K a s an equilibrium between 73% trans-fused and 27% 0-inside cis-fused conformers. cis-(H-1, H-8a)-1 -Alkylperhydrooxazolo-[3,4-a]pyridines (alkyl = methyl, ethyl, isopropyl) adopt equilibria heavily biased towards the trans-fused conformers, whereas the epimers adopt 18% 0-inside cis-fused e 82% transfused comformational equilibria at 183 K in CDCI,-CFCI,. At 190 K in CDCI, cis-(H-* Part 55 in the series 'Compounds with Bridgehead Nitrogen.' For Part 54, see Ref. 1.

6,

H-8a)-6-ethylperhydrooxazol0[3.4alpyridine adopts an equilibrium containing ca 3% transfused conformer in equilibrium with 97% 0-inside cis-fused conformer.

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