title: Nucleophilic substitution reactions of alcohols with use of montmorillonite catalysts as solid Brønsted acids.
abstract: We have developed an environmentally benign synthetic approach to nucleophilic substitution reactions of alcohols that minimizes or eliminates the formation of byproducts, resulting in a highly atom-efficient chemical process. Proton- and metal-exchanged montmorillonites (H- and Mn+-mont) were prepared easily by treating Na+-mont with an aqueous solution of hydrogen chloride or metal salt, respectively. The H-mont possessed outstanding catalytic activity for nucleophilic substitution reactions of a variety of alcohols with anilines, because the unique acidity of the H-mont catalyst effectively prevents the neutralization by the basic anilines. In addition, amides, indoles, 1,3-dicarbonyl compounds, and allylsilane act as nucleophiles for the H-mont-catalyzed substitutions of alcohols, which allowed efficient formation of various C-N and C-C bonds. The solid H-mont was reusable without any appreciable loss in its catalytic activity and selectivity. Especially, an Al3+-mont showed high catalytic activity for the alpha-benzylation of 1,3-dicarbonyl compounds with primary alcohols due to cooperative catalysis between a protonic acid site and a Lewis acidic Al3+ species in its interlayer spaces.
authors.affiliation: Department of Materials Engineering Science, Graduate School of Engineering Science and Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyana, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Motokura
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Nakagiri
authors.forename: Tomoo
authors.initials: T
authors.lastname: Mizugaki
authors.forename: Kohki
authors.initials: K
authors.lastname: Ebitani
authors.forename: Kiyotomi
authors.initials: K
authors.lastname: Kaneda