acids have been regioselectively prepared from the corresponding bicyclic monoesters. The subsequent cyclisation by thionyl chloride produced the desired bridged azatricyclic anhydrides which are versatile substrates for the synthesis of dipeptides; they are also converted into oxathymine and oxauracil by a thermal [4+2] cycloreversion.
已经从相应的双环单酯区域选择性地制备了桥连的N-保护的β-
氨基酸。随后被亚
硫酰氯环化,产生了所需的桥连氮杂三
环酸酐,它们是合成二肽的通用底物;它们还可以通过热[4 + 2]环还原反应转化为草胺和草酰
嘧啶。