Spectroscopic and structural studies of quinoline derivatives—II. Forrier transform i.r. spectroscopy. 1. Rotational isomerism in 3-ethoxycarbonyl-4(1H)-quinolone and some of its substituted derivatives
✍ Scribed by Julian Mirek; Zbigniew H. Urbanek
- Publisher
- Elsevier Science
- Year
- 1981
- Tongue
- English
- Weight
- 961 KB
- Volume
- 37
- Category
- Article
- ISSN
- 1386-1425
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✦ Synopsis
Ahsira~Rotational isomerism associated with internal rotation about the ring carbon(3)-ester carbonyl carbon single bond in a series of 3-ethoxycarbonyL4(1H)-quinoiones have been investigated spectroscopically in the solid state using Fourier transform i.r. and laser Raman spectroscopy. Particular attention is given to the 1700, 1300 and 11OOcm~' spectral regions related primarily to the vibrations of the CO,CxH, group. Within these regions rotational isomerism appeared in the compounds examined. The conformational changes are discussed and evidence is reported for occurrence of the unsubstituted compound 1 itself in the solid state at ambient temperature as an equilibrium mixture of both the s-nuns (la) and s-cis (lb) rotamers (this is in contrast to previous findings), and of its Bz-substituted derivatives. 1. INI'RODUCTlON *J. MOSZEW and Z. H. URBANEK, Zesz. Nauk. Uniw. Jogiellon., Pr. Chem. 2.11, 55 (1969) is now regarded as Part I.