Stereospecific and stereodivergent construction of tertiary and quaternary carbon centers through switchable directed/nondirected allylic substitution.

This study introduces the ortho-diphenylphosphanylbenzoate (o-DPPB)/o-DPPB oxide system as a switchable directing/nondirecting leaving group in a copper-mediated allylic substitution with Grignard and organozinc reagents. With this system, the regioselective, stereospecific, and stereodivergent construction of quaternary as well as tertiary carbon centers is possible in a reliable and predictable fashion. Starting from one substrate enantiomer, both optical antipodes of the substitution products are readily available.

o-DPPB-directed copper-mediated and -catalyzed allylic substitution with Grignard reagents.

The ortho-diphenylphosphanylbenzoyl (o-DPPB) group was explored as a directing leaving group in copper-mediated and copper-catalyzed allylic substitution with Grignard reagents. Complete control of chemo-, regio- and stereoselectivity with complete syn-1,3-chirality transfer was observed as a result of the directed nature of the reaction. No excess of organometallic reagent is required and the directing group can be recovered quantitatively.

Directed regio- and stereoselective hydroformylation of mono- and 1,3-disubstituted allylic alcohols: a catalytic approach to the anti-aldol-retron.

Regioselective and diastereoselective hydroformylation of mono- and 1,3-disubstituted allylic alcohol o-DPPB esters is described. The products represent synthetically important anti-aldol retrons.

Efficient transformation of Dictyostelium discoideum with a particle inflow gun.

We report experiments to transform Dictyostelium discoideum using a simple home-made particle gun. Stable transformants were obtained at frequencies of up to 2500 clones/microg DNA. This is five times more than we achieve with the same vector using electroporation protocols.

Ballistic transformation of Caenorhabditis elegans.

A novel method to transform the nematode Caenorhabditis elegans is described. DNA coprecipitated with gold particles is shot at worms by means of a helium beam. Transformed worms are either identified by a dominant visible marker or selected by a conditional lethal system.