References
- Büchi , G. and Yang , N. C. 1957 . J. Am. Chem. Soc. , 79 : 2318
- de Mayo , P. , Stothers , J. B. and Yip , R. W. 1961 . Can. J. Chem. , 39 : 2135
- Ishii , K. , Mathies , P. , Nishio , T. , Wolf , H. R. , Frei , B. and Jeger , O. 1984 . Helv. Chim. Acta , 67 : 1175
- Arylidene-β-ionones (4a-j) were prepared by condensing freshly-distilled β-ionone with distilled/crystallised aldehydes in the presence of 10% NaOH water-ethanol solution. The products were purified through chromatography over silica gel (hexane, hexane-benzene gradient) and/or by crystallization (yield, ∼ 90%), and characterised through spectral data (UV,ir, 1H nmr, 13C nmr and mass).
- 1H nmr data of 5a is as follows: δ 7.43–7.10 (m,5H, aromatic Hs), 6.78 & 6.35 (AB quartet, 2H,J=15.87 Hz,C′1-H & C′2-H), 5.75 (d,1H,J=6.52 Hz,C5-H), 5.27 (d,1H,J=6.52 Hz, C4-H), 2.21–1.08 (envelope with methyl singlets at δ 1.34, 1.18 and 1.11).Similar 1H nmr data were obtained for other pyrans (5b-j).