Reaction of 1,3-dicyanobenzene with β-amino alcohols (S)-H 2 NCHRCH 2 OH (R ) i Pr, i Bu, t Bu, CH 2 Cy, CH 2 Ph) and (R)-H 2 NCHPhCH 2 OH gave new 1,3-bis(2′-oxazolinyl)benzenes (30-51%). These, together with 1,3-bis(4′,4′-dimethyl-2′-oxazolinyl)benzene, were treated with LDA/TMEDA followed by the addition of PdBr 2 (1,5-COD) to give [2,6-bis(2′-oxazolinyl)phenyl]palladium(II) bromide complexes (21-41%). In two cases no complexes were obtained (R ) Ph, CH 2 Ph) due to ring opening of the oxazolines by LDA/TMEDA. Treatment of the palladium complexes with AgBF 4 , AgOTf, or AgSbF 6 in wet CH 2 Cl 2 provided a series of cationic [2,6-bis(2′-oxazolinyl)phenyl]palladium complexes (28-87%) containing water coordinated to palladium, as established by an X-ray crystal structure analysis of (S,S)-[2,6bis(4′-isopropyl-2′-oxazolinyl)phenyl]aquopalladium(II) trifluoromethanesulfonate. All of the cationic complexes proved to be efficient catalysts for the Michael reaction between R-cyanocarboxylates and methyl vinyl ketone and between acrylonitrile and activated Michael donors. Selectivities of up to 34% ee were obtained for the formation of (R)-ethyl 2-cyano-2-methyl-5-oxohexanoate.

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Synthesis and Application of Cationic 2,6-Bis(2-oxazolinyl) phenylpalladium(II) Complexes.-A series of cationic Pd(II)-complexes are synthesized, which markedly increase the rate of Diels-Alder reactions (→ (III)/(IV)), Michael additions (→ (VII)) and aldol reactions (→ (X)/( XI)). -(STARK, M. A.; RICHARDS, C. J.; Tetrahedron Lett. 38 (1997) 33, 5881-5884; Dep. Chem., Univ. Wales Coll., Cardiff CF1 3TB, UK; EN)