Palladate salts from chiral pyridinium ionic liquids: Synthesis and crystal structures
This paper reports the preparation, characterization and the crystal X-ray structures of metal-containing ionic liquid complexes based on chiral pyridinium cations and tetrachloropalladate (II) [PdCl4]2-.
New pyridinium chiral ionic liquids have been synthesised from the corresponding pyridine and chiral primary amines. The physical properties of these salts were determined; one of the salts is a room-temperature ionic liquid thermally stable up to 215 °C and suitable for organic synthesis.
Modified fry cyanation of a chiral pyridinium salt: Asymmetric syntheses of (-)-coniine and (-)-solenopsin A
The synthesis of chiral 2-cyano-Δ4-tetrahydropyridine 5 was carried out in 85 % yield through a modified two-step Fry reductive cyanation of pyridinium salt (+)-3c that used lithium triethylborohydride as the hydride donor. An alkylation-reduction sequence provided 2-alkyl-substituted tetrahydropyridines (+)-10a and (+)-10b in 72-75 % yield after chromatographic purification. This protocol has been applied to the asymmetric syntheses of piperidine alkaloids (-)-coniine and (-)-solenopsin A. The two-step reductive cyanation of chiral pyridinium salt (+)-3c afforded α-amino nitrile 5 in 85 % yield, which underwent an alkylation-reduction sequence followed by removal of the chiral moiety to yield the hemlock alkaloid (-)-coniine as its mandelate salt (>99:1 er). This reaction sequence was also used for the synthesis of the trans-2,6-disubstituted piperidine alkaloid (-)-solenopsin A. Copyright
Vu, Van Ha,Jouanno, Laurie-Anne,Cheignon, Adele,Roisnel, Thierry,Dorcet, Vincent,Sinbandhit, Sourisak,Hurvois, Jean-Pierre
p. 5464 - 5474
(2013/09/02)
Synthesis of chiral isoquinuclidines and determination of their absolute configuration