Boron Trifluoride-assisted Reactions of 1-Benzothiophen-3(2 H )-one with Various Ketones: A Convenient Entry to 2-Methylene-1 -benzothiophen-3(2 H )-one and/or 6 H -Di[1]benzothieno[3,2- b :2,3- e ]pyran Derivatives
Free accessResearch articleFirst published online September, 1999
Boron Trifluoride-assisted Reactions of 1-Benzothiophen-3(2 H )-one with Various Ketones: A Convenient Entry to 2-Methylene-1 -benzothiophen-3(2 H )-one and/or 6 H -Di[1]benzothieno[3,2- b :2,3- e ]pyran Derivatives
The title compounds are obtained in moderate to high yields by BF3-assisted reaction of 1-benzothiophen-3(2H)-one with nine ketones in diethyl ether at room temperature; the relative amounts of pyran 1 and ylidene 2 prove to be dependent upon electronic and steric factors.
References
1.
AhlmeinM., BarzoukasM., BedworthP. V., Blanchard-DesceM., FortA., HuZ-Y, MaderS. R., PerryJ. W. and RusnerC., Science, 335, 271, 1996.
2.
CaponB. and KwokF. C., Tetrahedron Lett., 1986, 27, 3275;
3.
ElgueroJ., MarzinC., KatritzkyA. R. and LindaP., The Tautomerism of Heterocyclic Compounds, Academic Press, New York, 1976.
4.
RajappaS., Comprehensive Heterocyclic Chemistry, ed. KatritzkyA. R. and ReesC. W., Pergamon, Oxford, 1984, vol. 4, ch. 3.14, p. 822;
5.
RéamonnL. S. S. and O'SullivanW. I., J. Chem. Soc., Perkin Trans. 1, 1977, 1009;
6.
IddonB. and ScrowstonM., Adv. Heterocycl. Chem., 1970, 11, 177.
7.
MarchJ., Advanced Organic Chemistry, Wiley, New York, 4th edn., 1992, p. 937.
