title: Directed ring-opening of 1,5-dioxaspiro[3.2]hexanes: selective formation of 2,2-disubstituted oxetanes.
abstract: 1,5-Dioxaspiro[3.2]hexanes undergo ring-opening reactions with many heteroatom nucleophiles to provide alpha-substituted-beta'-hydroxy ketones. However, certain Lewis acidic nucleophiles provide 2,2-disubstituted oxetanes. Herein, the results of reactions of 3-phenyl-1,5-dioxaspiro[3.2]hexane with a variety of nitrogen-containing heteroaromatic bases are reported. There appears to be a correlation between the pK(a) of the nucleophile and the reaction outcome with more acidic nucleophiles providing 2,2-disubstituted oxetanes. Moreover, the mode of ring opening can be directed toward the substituted oxetane by the addition of a Lewis acid. These results are rationalized by calculation of stationary points on the potential energy surfaces for the various possible reaction pathways using ab initio molecular orbital methods.
authors.affiliation: Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, USA.
authors.forename: Rosa
authors.initials: R
authors.lastname: Taboada
authors.forename: Grace G
authors.initials: GG
authors.lastname: Ordonio
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Ndakala
authors.forename: Amy R
authors.initials: AR
authors.lastname: Howell
authors.forename: Paul R
authors.initials: PR
authors.lastname: Rablen