Chiral quaternary ammonium phenoxides derived from cinchona alkaloids were easily synthesized and were effectively employed in the tandem Michael addition and lactonization between α,β-unsaturated ketones and a silyl enolate derived from phenyl isobutyrate, and optically active 3,4-dihydropyran-2-ones were afforded in high yields with high enantiomeric excesses.
从
金鸡纳
生物碱中提取的手性季
铵苯氧基化合物很容易合成,并被有效地用于α,β-不饱和酮和
异丁酸苯酯的
硅烯酸酯之间的串联迈克尔加成和内酯化反应,以高产率和高对映体过量获得了具有光学活性的
3,4-二氢吡喃-2-酮。