Three of these have been converted to the 4-alkylideneglutamic acids, 1, 2 and 3, which are identical to known natural products, the synthesis confirming 2 and 3 as the E-isomers. Catalytic reduction of the 4-alkylidenepyroglutamate derivatives 8 is stereospecific and affords an effective route to (2S,4S)-4-alkylglutamic acids and (2S,4S)-4-alkylprolines. Cuprate addition to the enone 5 affords access
已经发现由(2S)-焦谷
氨酸制备的烯胺酮4以明显的1,4-方式与D
IBAL和格利雅试剂反应,得到各种亚烷基衍
生物8,除
乙烯基衍
生物8e外,它们是仅作为(E)异构体形成。这些中的三个已被转化为与已知的
天然产物相同的4-亚烷基谷
氨酸1、2和3,合成证实2和3为E-异构体。催化还原4-亚烷基次谷
氨酸衍
生物8是立体定向的,并提供了通往(2 S,4 S)-4-烷基谷
氨酸和(2 S,4 S)-4-烷基脯
氨酸。向烯酮5中加入
铜酸盐可以进入(2 S,4 R)-差向异构体15,而卡宾的加入使得可以制备环丙基谷
氨酸32和33。