title: Benzotriazole-Assisted Aromatic Ring Annulation: Efficient and General Syntheses of Polysubstituted Naphthalenes and Phenanthrenes.
abstract: (Benzotriazol-1-ylmethyl)benzenes and -naphthalenes 1a-f, easily accessible from benzyl bromides and benzotriazole, readily undergo lithiation and subsequent 1,4-addition to alpha,beta-unsaturated aldehydes and ketones. Intramolecular cyclization of the products, induced by acetic acid-hydrobromic acid or polyphosphoric acid (PPA), followed by simultaneous dehydration and debenzotriazolylation furnishes a wide range of polysubstituted naphthalenes 7a-f and of phenanthrenes 9 and 11 in moderate to good yields in one-pot procedures. If compounds 1 are first lithiated and reacted with electrophiles, the resulting alkylation products undergo similar annulation reactions with alpha,beta-unsaturated carbonyl compounds to provide the more highly substituted naphthalenes 6a,b and phenanthrenes 10a,b in moderate overall yields.
authors.affiliation: Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200.
authors.forename: Alan R.
authors.initials: AR
authors.lastname: Katritzky
authors.forename: Guifen
authors.initials: G
authors.lastname: Zhang
authors.forename: Linghong
authors.initials: L
authors.lastname: Xie