David J. Gorin

The solutions with the problems regarding the ligand effects in homogeneous catalysis through December 2007 has been given. Specifically, the problems with the obvious differences in reactivity and selectivity that comes from changing neutral or anionic ligands will be addressed with a focus on ligands and complexes that enables enantioselective catalysis. There are at times when catalyst choice gives off better improvement within the reaction yields or efficiencies. Meanwhile, an emphasis will be given on the privileged ligands and catalysts for a given class of reactions. Finally, the Hayashi/Ito asymmetric aldol reaction will be dealt with.

A triphenylphosphinegold(I)-catalyzed cyclopropanation of olefins using propargyl esters as gold(I)-carbene precursors is reported. This reaction provided the basis for the use of a DTBM-SEGPHOS gold(I) complex as a catalyst in the enantioselective (up to 94% ee) preparation of vinyl cyclopropanes with high cis-selectivity.

Substituted pyrroles were prepared by a gold(I)-catalyzed acetylenic Schmidt reaction of homopropargyl azides. The reaction allows for regiospecific substitution at each position of the pyrrole ring under mild conditions. A mechanism in which azides serve as nucleophiles toward gold(I)-activated alkynes with subsequent gold(I)-aided expulsion of dinitrogen is proposed.

The rearrangement of 1-ethynyl-2-propenyl pivaloates to cyclopentenones catalyzed by cationic triphenylphosphinegold(I) complexes is described. The reaction tolerates both alkyl and aryl substitution at the acetylenic and olefinic positions. Importantly, the gold(I)-catalyzed rearrangement of enantioenriched propargyl pivaloates proceeds with excellent chirality transfer, thus providing a practical method for the enantioselective synthesis of cyclopentenones.