Diane Rix

Formation of quaternary chiral centers by N-heterocyclic carbene-Cu-catalyzed asymmetric conjugate addition reactions with Grignard reagents on trisubstituted cyclic enones.

The copper-catalyzed conjugate addition of Grignard reagents to 3-substituted cyclic enones allows the formation of all-carbon chiral quaternary centers. We demonstrate in this article that N-heterocyclic carbenes act as efficient chiral ligands for this transformation. High enantioselectivities (up to 96% ee) could be obtained for a variety of substrates.

CpRu-catalyzed O-H insertion and condensation reactions of α-diazocarbonyl compounds.

[CpRu(CH(3)CN)(3)][PF(6)] and diimine ligands catalyze together the decomposition of α-diazocarbonyl compounds leading to O-H insertion and condensation reactions. In comparison with Rh(II) and Cu(I) complexes, the CpRu catalysts produce rapid and often more selective reactions. Promising enantioselectivities are obtained in dioxole syntheses.

Macrocyclization of Oxetane Building Blocks with Diazocarbonyl Derivatives under Rhodium(II) Catalysis

Highly concentrated: The title reaction proceeds to afford a rare type of 15-membered polyether macrocycle in up to 84 % yield (R1=alkyl, alkoxy, O-allyl, OCH2CH2Ph; R2=alkyl, Ph; R3=H, Me, Et). This nontemplated macrocyclization is performed in a single pot under high concentration and precludes the usual polymerization.

Highly recoverable pyridinium-tagged Hoveyda-Grubbs pre-catalyst for olefin metathesis. Design of the boomerang ligand toward the optimal compromise between activity and reusability.

Whereas the boomerang ligand of Hoveyda-Grubbs pre-catalysts can be modified by attachment of a pyridinium tag to its benzylidene moiety, a precise adjustment of the length of the spacer allows the optimum balance to be reached between the activity of the catalyst and its recoverability, exceeding 98% after 6 catalytic runs in the best case.

Medium-Sized Rings versus Macrocycles through Rhodium-Catalyzed Ring-Expansion Reactions of Cyclic Acetals

α-Diazo β-ketoesters and diketones react with cyclic acetals under Rh(II) catalysis to yield unprecedented polyoxygenated 8- and 9-membered rings in one pot. The reactions occur under mild conditions with yields up to 90%. A perfect regioselectivity is obtained, which can be rationalized through a mechanistic hypothesis that considers 1) the formation of an oxonium ylide, 2) its transformation into an unsaturated acyclic oxocarbenium electrophilic intermediate, and 3) an intramolecular nucleophilic attack in a direct application of Baldwins rules.

Phosphate binding to the [Au(IPr)] moiety: inner vs. outer sphere coordination behaviour.

The synthesis and characterization of a new class of cationic (NHC)gold(I) (NHC = N-Heterocyclic carbene) complex containing the phosphate counterions TRISPHAT and TRISPHAT-N have been achieved. The selection of the appropriate hexacoordinated phosphate architecture permits the isolation of complexes bearing an inner or outer sphere anionic counterion.