Selective C-H bond activation and other reactions in water-soluble Host-Guest media

ORGN 245

Dorothea Fiedler1, Dennis H. Leung, leungd@uclink.berkeley.edu2, Michael D. Pluth, pluth@berkeley.edu3, Barbara Carl3, Vy M. Dong, vdong@berkeley.edu2, Kenneth Raymond, raymond@socrates.berkeley.edu4, and Robert G. Bergman, bergman@cchem.berkeley.edu2. (1) Department of Chemistry, University of California, San Francisco, San Francisco, CA 94143, (2) Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720-1460, (3) Department of Chemistry, UC Berkeley, Berkeley, CA 94720-1460, (4) Department of Chemistry, University of California, Berkeley, CA 94720-1460
Several cationic organic and organometallic complexes have been shown to bind into the cavities of water-soluble chiral clusters or “nanovessels” (constructed earlier by the K. N. Raymond group) from metal salts and dicatecholate bridging ligands. Among these are reactive Ir(III) complexes that undergo Ir(III)/Ir(V) C-H oxidative addition reactions (discovered earlier by the R. G. Bergman group) when they are encapsulated in the nanovessel clusters in aqueous solution, leading to the first nanovessel intracavity C-H activation reactions. Substantial size- and shape selectivities have been observed in these reactions. More recently, aza-Cope and other pericyclic rearrangements have been found to proceed in the nanovessel cavities. The ability of the products of these reactions to undergo rapid hydrolysis results in our ability to carry out the reactions in a catalytic fashion. The nanovessels catalyze the rearrangement/hydrolysis of the aza-Cope substrates with up to 1000-fold rate acceleration. Mechanistic studies have shown that in addition to size- and shape restrictions on binding cations into the nanovessel cavities, nanovessel-guest external ion-pairing also plays an important role in determining the rates of these reactions. Exploratory reactions on other types of reactions that can be carried out in the nanovessel cavities will also be discussed.

ACS Award in Organometallic Chemistry
8:55 AM-12:00 PM, Tuesday, 28 March 2006 Georgia World Congress Center -- Georgia Ballroom 2, Oral

Division of Organic Chemistry

The 231st ACS National Meeting, Atlanta, GA, March 26-30, 2006