3-Ethyl-3-methoxycarbonylmethylpiperidine (20) was prepared via the unsaturated aldehyde (12) derivel from benzyl 1, 6-dihydro-3 (2H)-pyridinone-1-carboxylate (5b). N-Chlorination of 20 and subsequent exposure to a base afforded rel-(2S, 3R)-3-ethyl-2-hydroxypiperidine-3-acetic acid γ-lactone (3) in a good yield. According to the known method, the lactone (3) was converted into (±)-eburnamonine (1) and (±)-epieburnamonine (31). A possible pathway from 20 to 3 is also discussed.
3-乙基-3-甲氧羰基甲基
哌啶(20)是通过 1,6-二氢-3(2H)-
吡啶酮-1-
甲酸苄基酯(5b)衍生出的不饱和醛(12)制备的。将 20 N-
氯化并随后与碱接触,可以得到 rel-(2S,3R)-3-乙基-
2-羟基哌啶-3-
乙酸γ-内酯(3),收率很高。根据已知的方法,内酯(3)被转化为(±)-伯纳摩宁(1)和(±)-表伯纳摩宁(31)。此外,还讨论了从 20 到 3 的可能途径。