October 29, 2009

A New Porous Reaction Layer for Developing Addressable Molecular Libraries

Libo Hu, Jennifer L. Bartels, Jeremy W. Bartels, Karl Maurer and Kevin D. Moeller

J. Am. Chem. Soc., 2009, 131(46), 16638–16639

A new diblock copolymer-derived porous reaction layer for microelectrode arrays has been tested for its stability and its compatibility with both site-selective synthesis and electrochemical signaling experiments. The diblock copolymer consisted of a cinnamoyl-substituted polymethacrylate block for attachment to the surface of the array and a bromo-substituted polystyrene block for selective functionalization of the surface proximal to microelectrodes in the array. Site-selective Suzuki, Heck, and Cu(I)-coupling reactions were all performed on the new reaction layer along with electrochemical impedance studies.


September 11, 2009

Anodic Oxidations and Polarity: Exploring the Chemistry of Olefinic Radical Cations

Feili Tang and Kevin D. Moeller

Tetrahedron, 2009, 65(52), 10863-10875

The cyclization chemistry of radical cations derived from electron-rich olefins has been examined and the relationship between the polarization of the radical cation and the chemoselectivity of the reaction probed. It was found that more polarized radical cations favor carbon–carbon bond formation while less polarized radical cations favor carbon–heteroatom bond formation. A new approach to the synthesis of quaternary carbons was uncovered and the compatibility of ene diol ethers with anodic olefin coupling reactions examined.


July 6, 2009

Building Addressable Libraries: Site-Selective Lewis-Acid (Sc(III)) Catalyzed Reactions

Bo Bi, Karl Maurer, and Kevin D. Moeller.
Angew. Chem. Int. Ed. Eng. 2009, 48, 5872

Lewis acid-catalyzed reactions have been site-selectively conducted on arrays having either 1024 microelectrodes cm-2 or 12,544 microelectrodes cm-2. The reactions employ Sc(III) generated at the microelectrodes as the Lewis acid, and confine the reagent to the electrodes utilized in its generation with the use of  2-phenylbenzthiazole  as a solution phase reductant. A multicomponent synthesis of a tetrahydropyran, a Diels-Alder reaction, and an esterification reaction were all shown to be compatible with the electrochemical generation of the Sc(III) and the confinement strategy.


March 1, 2009

Intramolecular Anodic Olefin Coupling Reactions: Using Radical Cation Intermediates to Trigger New Umpolung Reactions

Kevin D. Moeller
Synlett, 2009, 1208-1218

Anodic electrochemistry is a powerful tool for generating radical cation intermediates and initiating new cyclization reactions. Like most electrochemical reactions, the transformations involve umpolungs. In this review, recent studies examining the intramolecular coupling of radical cations derived from enol ethers, vinyl sulfides, and ketene acetals with carbon, oxygen, and nitrogen trapping groups are discussed to highlight their synthetic potential.


February 24, 2009

Building Addressable Libraries: Site-Selective Suzuki Reactions on Microelectrode Arrays

Libo Hu, Karl Maurer and Kevin D. Moeller

Org. Lett., 2009, 11 (6), pp 1273–1276

A site-selective Suzuki reaction has been developed for use on microelectrode arrays. The reaction conditions employed are similar to those used to achieve site-selective Heck reactions. The reaction can be run with either an aryliodide attached to the surface of the array and an arylboronic acid in solution or with an arylboronic acid attached to the surface of the array and an arylbromide in solution. Both allyl acetate and air are effective confining agents for the reaction. The reactions are compatible with arrays containing either 1024 microelectrodes cm-2 or 12,544 microelectrodes cm-2.