title: General and efficient insertion of carbons carrying benzotriazole.
abstract: Anions formed from the lithiation of 1-(1-benzotriazolylalkyl)benzotriazoles (1, 6) and 1-(1-methylthioalkyl)benzotriazoles (10 and 10a) with n-BuLi underwent additions to cyclic and acyclic ketones giving intermediates 3a-f, 7b-f, and 11b-d, respectively, in excellent yields. Thermal rearrangements of intermediates 3a,b,d-f and 7b-d,f in the presence of zinc bromide provided one-carbon chain-extended or ring-expanded alpha-benzotriazolyl ketones 4a,b,d-f and 8b-d,f in moderate yields with excellent regioselectivity. By contrast, intermediates 11b-d on treatment with zinc bromide loose a molecule of benzotriazole followed by intramolecular cyclization of the resulting intermediates 12b-d to provide the 2,3- and 1,2,3-substituted indenes 13b-d in good yields.
authors.affiliation: Center for Heterocyclic Compounds, University of Florida, Department of Chemistry, Gainesville, Florida 32611-7200, USA. katritzky@chem.ufl.edu
authors.forename: Alan R
authors.initials: AR
authors.lastname: Katritzky
authors.forename: Sergey
authors.initials: S
authors.lastname: Bobrov
authors.forename: Kostyantyn
authors.initials: K
authors.lastname: Kirichenko
authors.forename: Yu
authors.initials: Y
authors.lastname: Ji