Synthesis of chiral 1,5-disubstituted pyrrolidinones via electrophile-induced cyclization of 2-(3-butenyl)oxazolines derived from (1R,2S)- and (1S,2R)-norephedrine
作者:Iván Kanizsai、Zsolt Szakonyi、Reijo Sillanpää、Matthias D’hooghe、Norbert De Kimpe、Ferenc Fülöp
DOI:10.1016/j.tetasy.2006.11.006
日期:2006.11
Starting from (1R,2S)- and (1S,2R)-norephedrine, enantiomers of the corresponding 2-(3-butenyl)oxazolines were prepared in a two-step process. The cyclization of the intermediate alkenylamides with phenylselenyl bromide afforded cyclic imidates instead of the expected pyrrolidinones. The electrophile-induced cyclizations of 2-alkenyloxazolines with bromine or iodine produced diastereomeric mixtures of
从(1 R,2 S)-和(1 S,2 R)-去氧麻黄碱开始,以两步法制备相应的2-(3-丁烯基)恶唑啉的对映体。中间烯基酰胺与苯基硒基溴化物的环化反应提供了环状酰亚胺,而不是预期的吡咯烷酮。2-烯基恶唑啉与溴或碘的亲电诱导的环化反应生成了手性1,5-二取代的吡咯烷酮的非对映异构体混合物。顺式(1 R,2 S,5 R)-非对映异构体7与NaH的闭环生成四氢吡咯并[2,1 - b ]恶唑-5-酮衍生物图18是由(1R,2S)-去氧麻黄碱与乙酰丙酸的环缩合制备的。