Novel syntheses of the carbapenem key intermediates, (3R,4R)-4-acetoxy-3-[(R)-1-(t-butyldimethylsilyloxy)ethyl]-2-azetidinone and (3S,4R)-3-[(R)-1-(t-butyldimethylsilyloxy)ethyl]-4-carboxymethyl-2-azetidinone, from (S)-ethyl lactate
作者:Yoshio Ito、Yuko Kobayashi、Takeo Kawabata、Mitsuru Takase、Shiro Terashima
DOI:10.1016/s0040-4020(01)89105-5
日期:1989.1
Two types of the carbapenem key intermediates (4 and 6) have been efficiently synthesized from inexpensive (S)-ethyl lactate (7). Thus, (S)-2-benzyloxypropanal readily obtainable from 7 was condensed with di-p-anisylmethylamine to give the chiral imine. The [2+2]-cycloaddition reaction of diketene with the imine underwent in a highly stereoselective manner, yielding the desired 3,4-trans-3-acetyl-β-lactam
两种类型的碳青霉烯关键中间体(4和6)是由廉价的(S)-乳酸乙酯(7)有效合成的。因此,将容易从7得到的(S)-2-苄氧基丙醛与二对茴香基甲胺缩合,得到手性亚胺。双烯酮与亚胺的[2 + 2]-环加成反应以高度立体选择性的方式进行,产生了所需的3,4-trans-3-乙酰基-β-内酰胺(13a)作为主要产物(非对映选择性为7-10: 1)。这分别以9个步骤和6个步骤进行了详细说明,分别为4和6。