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2005
Enantioselective syntheses
O 0031
Chiral Thiazoline Ligands: Application in Pd-Catalyzed Allylic Substitution. —
series of optically active thiazoline ligands (I)—(VII) is tested in the Pd-catalyzed
03- 034 A
reaction of acetate (VIII) with malonate (IX). The results are compared with those obtained by use of the corresponding well-known oxazolines. In some cases, the behavior
of the thiazoline and oxazoline ligands is very different with a view to catalytic activity
and enantiomeric excess. Bis(thiazolines) are found to be globally more active than
bis(oxazolines) and furnish good enantioselectivity (up to 88%), except for ligand (VI)
which is completely inefficient. Pyridyl- and quinolylthiazolines are quite similarly to
the corresponding oxazolines concerning the enantioselectivity, but are less active. An
exception in this series is (S)-2-pyridyl-4-tert-butylthiazoline which affords superior
enantioselectivity. In contrast to the phosphine oxazoline ligand which is one of the best
ligands for this reaction, ligand (VII) shows very disappointing results. —
(ABRUNHOSA, I.; DELAIN-BIOTON, L.; GAUMONT, A.-C.; GULEA*, M.;
MASSON*, S.; Tetrahedron 60 (2004) 41, 9263-9272; Lab. Chim. Mol. Thio-Org.,
CNRS, Inst. Sci. Matiere Rayonnem., Univ. Caen, F-14050 Caen, Fr.; Eng.) — Klein
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