Preparation of Chiral Hydroxy Carbonyl Compounds and Diols by Ozonolysis of Olefinic Isoborneol and Fenchol Derivatives: Characterization of Stable Ozonides by 1H-, 13C-, and 17O-NMR and Electrospray Ionization Mass Spectrometry
✍ Scribed by Kalina Kostova; Vladimir Dimitrov; Svetlana Simova; Manfred Hesse
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- German
- Weight
- 193 KB
- Volume
- 82
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
The allylic and homoallylic alcohols 1 ± 8, prepared from ()-camphor and (À)-fenchone, were ozonized in Et 2 O at À788 and treated with Et 3 N or LiAlH 4 to give the chiral hydroxy carbonyl compounds 9 ± 16 and the diols 17 ± 24, respectively (Scheme 1). In the case of the diols 19 and 24, the formation of new chiral centers proceeded with high diastereoselectivity. These diols were prepared highly diastereoselectively also by LiAlH 4 reduction of the hydroxy carbonyl compounds 11 and 16a, respectively ( Scheme 2). The absolute configuration of the new chiral centers in 19 and 24 was determined by X-ray and NMR methods. The ozonization of compounds 2, 3, 7, and 8 provided the relatively stable hydroxy-substituted 1,2,4-trioxolane derivatives (ozonides) 37 ± 40 ( Scheme 5) which were characterized by 1 H-and 13 C-NMR spectra, ESI-MS, and naturalabundance 17 O-NMR spectra.
Helvetica Chimica Acta ± Vol. 82 (1999) 1386 1 ) Arbitrary or trivial numbering; for systematic names, see Exper. Part.
2 ) For spectral data of 25, see Table and Exper. Part.
Scheme 2
3 ) The ferrocenyllithium reagent was prepared by lithiation of ferrocene with BuLi ´TMEDA (Cp 2 Fe/BuLi/ TMEDA 1 : 2.2 : 1.2; TMEDA N,N,N',N'-tetramethylethylenediamine); the ratio ( LiCp) 2 Fe/Li(Cp)-Fe(Cp) 30 : 1 was determined by the procedure described in [14a].