37 research outputs found
Ligand Effects in Gold- and Platinum-Catalyzed Cyclization of Enynes: Chiral Gold Complexes for Enantioselective Alkoxycyclization
No full textPhosphine and bidentate N-N ligands inhibit the Alder-ene-type cycloisomerization of enynes catalyzed by Pt(II) and favor the alkoxycyclization process. The enantioselective Pt(II)-catalyzed alkoxycyclization has been studied in the presence of chiral mono- and bidentate phosphines, as well as chiral bidentate N-N ligands. Modest levels of enantioselection (up to 50% ee) have been obtained with Tol-BINAP as ligand. The alkoxycyclizations with a catalyst formed from [Au(L)Cl]/AgX proceed more readily, and up to 94% ee's have been obtained using [(AuCl)2(Tol-BINAP)] ( 47 ) as the precatalyst. The X-ray crystal structures of Au(I) complexes 47 and chloro-(R)-2-(tert-butylsulfenyl)-1-(diphenylphosphino)ferrocene gold(I) ( 39 ) show the AuCl fragments monocoordinated with the P centers of the chiral phosphine ligands
Solid-Phase Synthesis of a Peptide-Based P,S-Ligand System Designed for Generation of Combinatorial Catalyst Libraries
No full textSynthesis of Sulfoximine Carbamates by Rhodium-Catalyzed Nitrene Transfer of Carbamates to Sulfoxides
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Catalytic Enantioselective Approach to the Stereodivergent Synthesis of (+)-Lasubines I and II
No full textFlexible Protocol for the Chemo- and Regioselective Building of Pyrroles and Pyrazoles by Reactions of Danishefsky’s Dienes with 1,2-Diaza-1,3-butadienes
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