Coordination chemistry with pyrazole-based chelating ligands: molecular structural aspects

Transition-metal-catalyzed processes that allow the efficient coupling of three reactive components in a chemoselective and stereoselective fashion are particularly useful in the synthesis of complex organic molecules from simple, readily available substrates. This account outlines work primarily from the author's laboratory on the development of nickel-catalyzed multicomponent coupling processes. An overview of new synthetic methods, a discussion of potential mechanisms, and a description of applications in complex-molecule synthesis are provided.

Nickel-Catalyzed Cyclizations, Couplings, and Cycloadditions Involving Three Reactive Components

Arylboronic acids underwent the conjugate 1,4-addition to alpha, beta-unsaturated esters to give beta-aryl esters in high yields in the presence of a rhodium(I) catalyst. The addition of arylboronic acids to isopropyl crotonate resulted in high yields and high enantioselectivity exceeding 90% ee in the presence of 3 mol % of Rh(acac)(C(2)H(4))(2) and (S)-binap at 100 degrees C. The rhodium/(S)-binap complex provided (R)-3-phenylbutanoate in the addition of phenylboronic acid to benzyl crotonate. The effects on the enantioselectivity of chiral phosphine ligands, rhodium precursors, and substituents on alpha,beta-unsaturated esters are discussed, as well as the mechanistic aspect of the catalytic cycle.

Asymmetric conjugate 1,4-addition of arylboronic acids to alpha, beta-unsaturated esters catalyzed by Rhodium(I)/(S)-binap

Disclosed are compounds of Formula (I), methods of using the compounds as immunomodulators, and pharmaceutical compositions comprising such compounds The compounds are useful in treating, preventing or ameliorating diseases or disorders such as cancer or infections

Debora J. Ellis

Papers

Modeling the active site in hemocyanin: Synthesis and reactivity of binuclear copper complexes

3,3'-Disubstituted 2,2'-biphenols. Synthesis of nonplanar, tetradentate chelating ligands

Synthesis of dioxomolybdenum(VI) complexes of heterocyclic-N,O and-N,S ligands