Diastereoselective Diels-Alder reactions of (S,S)-2-(3,5-dimethylmorpholino) butadienes 10 with aza-dienophiles are described, leading to cycloadducts 12 in good yields and high stereoselectivities (de = 87-96%). After double bond migration to 13, acidic and basic hydrolysis affords 4-oxohexahydropyridazine derivatives 14 and 16 of high enantiomeric purity (ee = 90-91%). The configuration of the new stereogenic centre is determined by NOE-measurements and an X-ray structure analysis of the cycloadduct (R,S,S)- 13f.
描述了(S,S)-2-(
3,5-二甲基吗啉基)
丁二烯 10 与氮杂二烯烃的非对映选择性 Diels-Alder 反应,从而得到产率高、立体选择性高(de = 87-96%)的环状产物 12。双键迁移到 13 后,酸性和碱性
水解可得到对映体纯度很高(ee = 90-91%)的 4-氧代
六氢哒嗪衍
生物 14 和 16。新立体中心的构型是通过 NOE 测量和环加成物 (R,S,S)- 13f 的 X 射线结构分析确定的。