Selective monoacylation of ferrocene . An eco-friendly procedure on the solid phase of alumina

Abstract

A simple, efficient and environment-friendly procedure has been developed for acylation of ferrocene with direct use of carboxylic acid in the presence of trifluoroacetic anhydride on the solid phase of alumina. A wide range of structurally varied carboxylic acids have been found to provide selectively the monoacylated products in high yields.

References

1. (a) A. Togni, Angew. Chem., Int. Ed. Engl., 1996, 35, 1475; (b) H. B. Kagan, P. Ditter, A. Gref, D. Guillaneux, A. Masson-Szymczak, F. Rebiere, O. Riant, O. Samuel and S. Tauden, Pure Appl. Chem., 1996, 68, 29; (c) S.-I. Fukuzawa and H. Kato, Synlett, 1998, 727; (d) W. G. Jary and J. Baungartner, Tetrahedron: Asymmetry, 1998, 9, 2081.
2. (a) A. M. Giroud-Godquin and P. M. Maitlis, Angew. Chem., Int. Ed. Engl., 1991, 30, 375; (b) A. Riklin, E. Katz, I. Willner, A. Stocker and A. F. Brueckmann, Nature, 1995, 376, 672.
3. (a) L. Schwink, S. Vettel and P. Knochel, Organometallics, 1995, 14, 5000; (b) S. Bhattacharyya, Synlett, 1998, 837 and references therein.
4. (a) K. Plesske, Angew. Chem., Int. Ed. Engl., 1962, 1, 312; (b) D. E. Bublitz, K. L. Rinehart, Jr., in Organic Reactions, John Wiley, New York, 1969, 17, 23 and references therein; (c) R. Vukicevic, Z. R. Ratkovic, M. D. Vukicevic and S. K. Konstantinovic, Tetrahedron Lett., 1998, 39, 5837 and refer-ences therein.
5. B. C. Ranu, K. Ghosh and U. Jana, J. Org. Chem., 1996, 61, 9546.
6. With 1 equivalent of carboxylic acid and 1 equivalent of trifluoroacetic anhydride the reaction is considerably slow and the conversion is also not complete even after 12 h. However, use of 2 equivalents of carboxylic acid and 2.5 equivalents of TFAA accelerated the reaction to a great extent producing only the monoacylated product. But, interestingly, use of 4 equivalents of carboxylic acid and 8 equivalents of TFAA leads to diacylation quantitatively (2 examples) although the condition is yet to be generalised.