On treatment with 10% HF, butenolides 4a and 4b afforded enantiopure (−)-syringolides 1 (1a) and 2 (1b) respectively in much higher yields. Unprecedentedly, the cyclic acetal 5a was also converted to 1a by reacting with an excess of p-TsOH. The structure of the synthetic (−)-syringolide 1 (1a) was substantiated by an X-ray crystallographic study.
在用10%HF处理时,
丁烯内酯4a和4b分别以高得多的产率提供了对映纯(-)-丁香油酯1(1a)和2(1b)。前所未有地,通过与过量的p-TsOH反应,环状
缩醛5a也被转化为1a。通过X射线晶体学研究证实了合成的(-)-丁香油精1(1a)的结构。