UC Santa Barbara

I. A new biaryl phosphine-containing ligand from an active palladium catalyst for ppm level Suzuki-Miyaura couplings, enabled by aqueous micellar reaction medium is presented. A wide array of functionalized substrates including aryl/heteroaryl bromides are amenable, as are, notably, chlorides. The catalytic system is both general and highly effective at low palladium loadings (1000-2500 ppm or 0.10-0.25 mol%). Density functional theory calculations suggest that greater steric congestion in N2Phos induces increased steric crowding around the Pd center, helping destabilize the 2:1 ligand-Pd0 complex for N2Phos then previously described ligands, and thereby favoring the formation of the 1:1 ligand-Pd0 complex that is more reactive in the oxidative addition of aryl chlorides.

II. Previous studies have shown that aqueous solutions of designer surfactants enable a wide verity of valuable transformations in synthetic organic chemistry. Since reactions take place within the inner hydrophobic cores of the aggregate nanoreactors, and products made therein are in dynamic exchange between micelles through in water, opportunities exist to use enzymes to participate in multi-step chemo- and bio-catalytic processes. Herein, studies conducted utilizing the oxidoreductase class of enzymes are presented. Most noteworthy is the finding that aqueous micelles present in the water appear to function not only as a medium for both chemo- and bio-catalysis, but as a reservoir for substrates, products and catalysts, decreasing noncompetitive enzyme inhibition.

III. Two new methods for selective deprotection of diphenylmethylsilyl (DPMS) ethers are described. Unmasking can be achieved with either catalytic amounts of perfluoro-1-butanesulfonyl fluoride (a SuFEx reagent) under mild, aqueous conditions, or using stoichiometric amounts of 18-crown-6 ether in aqueous ethanol.