Synthesis and Investigation of C₂-Symmetric Optically Active Pyrrolidinium Salts as Chiral Phase-Transfer Catalysts

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C₂-Symmetric optically active pyrrolidinium salts were synthesized by the reaction of 2, 3 : 4, 5-di-O-benzylidene-(3R, 4R)-dihydroxy-(2S, 5S)-bis(hydroxymethyl)pyrrolidine (2), (3R, 4R)-dimethoxy-(2S, 5S)-bis(methoxymethyl)-pyrrolidine (3), 2, 3 : 4, 5-Di-O-benzylidene-(3R, 4R)-dihydroxy-N-(2-hydroxyethyl)-(2S, 5S)-bis(hydroxymethyl)-pyrrolidine (5), and (3R, 4R)-dimethoxy-N-(2-hydroxyethyl)-(2S, 5S)-bis(methoxymethyl)pyrrolidine (7) with methyl iodide or α, ω-dibromoalkanes. They exhibited low chiral induction activity in the epoxidation of chalcone and in the Darzens condensation of p-chlorobenzaldehyde and phenacyl chloride under phase-transfer conditions.