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.

Nucleophilic addition of sulfonamides and carboxamides to simple alkenes proceeded smoothly using a proton-exchanged montmorillonite catalyst. The spent catalyst was recovered easily from the reaction mixture and was reusable at least five times without any loss of activity. The unique acidity of the proton-exchanged montmorillonite (H-mont) catalyst was found to be applicable to additional reactions: substitution of hydroxyl groups of alcohols with amides and anilines.

Indium has received much attention as a widely used rare metal, which has led to its consumption and cost increasing dramatically. Development of economical and ecological procedures for indium recycling is highly desired in all fields consuming indium. Here, we propose that indium species can be immobilized on solid acids by ion exchange, which increases their activity and enables the generation of the first recyclable heterogeneous indium catalysts for addition reactions of 1,3-dicarbonyl compounds to unactivated alkynes. This reaction was first reported in 2003, as a typical green protocol using abundant carbon sources for useful fine chemicals. The In 3+ -exchanged ultrastable Y zeolite (In 3+ -USY) and montmorillonite (In 3+ -mont) showed various unique catalyses. For example, the alkenylation reaction proceeded successfully without any additives except for the catalysts.

Amination O 0268 Efficient C-N Bond Formations Catalyzed by a Proton-Exchanged Montmorillonite as a Heterogeneous Broensted Acid. -The reaction is applicable to a large variety of amines, unactivated alkenes and alcohols. The catalyst can be reused up to 5 times without loss of activity. -(MOTOKURA, K.; NAKAGIRI, N.; MORI, K.; MIZUGAKI, T.; EBITANI, K.; JITSUKAWA, K.; KANEDA*, K.; Org. Lett. 8 (2006) 20, 4617-4620; Dep. Mater. Eng. Sci., Grad. Sch. Eng., Osaka Univ., Toyonaka, Osaka 560, Japan; Eng.) -R. Steudel 04-043