Titanium-induced synthesis of benzofurans
Ketoesters derived from the acylation of o-hydroxyacetophenone with aliphatic as well as aromatic acid chlorides undergo intramolecular cyclization in the presence of low-valent titanium to afford benzofurans in good yields. The reduction of titanium trichloride with dry zinc powder in refluxing THF takes place in the presence of the ketoester which simultaneously cyclizes as the titanium catalyst is formed, rendering the pre-reduction of titanium trichloride in a separate step unnecessary.
KEY WORDS: Ketoesters, Low-valent titanium, Benzofurans
Bull. Chem. Soc. Ethiop. 2011, 25(1), 157-160.