title: On the Configurational Stability of Chiral Heteroatom-Substituted [D1]Methylpalladium Complexes as Intermediates of Stille and Suzuki-Miyaura Cross-Coupling Reactions.
abstract: Enantiomerically pure (S)-tributylstannyl[D1]methanol and (R)- and (S)-tributylstannyl[D1]methyl benzoates were Stille-coupled with bromobenzene and benzoyl chloride in 1,4-dioxane and toluene using [(Ph3P)4Pd] or [(Ph3P)2PdCl2] either alone or in combination with CuCN as cocatalyst at temperatures up to 80 °C. The products were found to be enantiomerically pure. (R)- and (S)-N-(tributylstannyl[D1]methyl)phthalimides gave enantiomerically pure products with benzoyl chloride, but with bromobenzene protected phenyl[D1]methylamines gave products of only 52-69 %eedepending on the solvent used. Tributyl(thio[D1]methyl)stannanes could not be Stille-coupled with benzoyl chloride or with bromobenzene. Similarly, dimethyl phenyl[D1]methylboronate underwent a Suzuki-Miyaura coupling with bromobenzene to give phenyl[D1]methylsilane with 99 %ee. All couplings followed a retentive course and, except in one case, the intermediate [XCHDPdLn] complexes were found to be microscopically configurationally stable.
authors.affiliation: Institute of Organic Chemistry, University of Vienna, Währingerstrasse 38, 1090 Vienna Austria.
authors.forename: Petra
authors.initials: P
authors.lastname: Malova Krizkova
authors.forename: Friedrich
authors.initials: F
authors.lastname: Hammerschmidt
keywords: Chi­rality; Cross-coupling; Enantioselectivity; Isotopic labeling; Palladium; Reaction mechanisms