Enantioselective Palladium-Catalysed Allylation of 1,5-Dimethylbarbituric Acid

Enantioselective Catalysis; 130: Optically Active Expanded Ligands Based on the trans-1,2-Substituted Cyclopentane Skeleton

“…Its 1 H NMR spectrum in DMSOd 6 showed two protons at δ = 6.92 with a strong coupling constant of 1 J H,P = 537 Hz indicating the predominance of The use of acetone as a transacetalization agent was not feasible for the ortho-substituted tetraacetals 5 and 8. When 5 was treated with aqueous acetone under acid catalysis no aldehyde but addition products of acetone were isolated.…”

“…In earlier reports [3][4][5] we tried to overcome some of the disadvantages of the classic phenylated ligands, such as lack of long-range influence on distant reaction sites, e.g. in the allylic alkylation of barbiturates, 6 by the dendrizyme concept. 7 In the first approaches to the design of expanded phosphanes a strongly chelating PPskeleton was equipped with dendritic substituents bearing multiple chiral units in the periphery.…”

Optically Active Transition Metal Complexes. 128 [1] Synthesis, Characterization and Molecular Structures of Cycloheptatrienyl-Iminphos-Molybdenum Complexes Differing Only in the Metal Configuration

“…Treatment of the reactive complex [(η 7 -C 7 H 7 )Mo(η 6 -C 6 H 5 CH 3 )]BF 4 [9] with the chiral phosphaneimine 2-[N-(S)-1-phenylethylcarbaldimino]phenyl(diphenyl)phosphane, (S)-iminphos [10,11], in CH 3 CN resulted in the formation of a diastereomer mixture of [(η 7 -C 7 H 7 )Mo(iminphos)(NCMe)]BF 4 (1) (Scheme 1). The diastereomer ratio could be determined by 1 H NMR spectroscopy as 55:45 in [D 6 ]acetone.…”

“…Elemental analyses: Elementar Vario EL III. Ϫ The (S)-iminphos ligand [10,11] and the complex [(η 7 -C 7 H 7 )Mo(η 6 -C 6 H 5 CH 3 )]BF 4 [9] were prepared according to the literature. (1).…”

Enantioselektive Katalyse, 121. Mitt. [1]: Chirale Phosphanliganden mit zusätzlichen Sauerstoffunktionalitäten

“…Zu Durchfu Èhrung, Aufarbeitung und Analytik der Katalysen siehe Ref. [21]. Die besten Ergebnisse wurden mit den Liganden 9 (2.3% ee (À)-Isomer, Base Chinin), 21 (1.7% ee (À)-Isomer, Base NEt 3 ) und 26 (3.8% ee ()-Isomer, Base NEt 3 ) erzielt.…”