Syntheses of Strychnan- and Aspidospermatan-Type Alkaloids. 9.<sup>1</sup> The Enantioselective Generation of Tetracyclic ABCE Intermediates by a Tandem Condensation, [3,3]-Sigmatropic Rearrangement, and Cyclization Sequence
作者:Martin E. Kuehne、Feng Xu
DOI:10.1021/jo970207j
日期:1997.11.1
tryptophan-derived benzyl 2-(benzylamino)-3-[3-[2-[(methoxycarbonyl)methyl]indolyl]]propionate gave tetracyclic hexahydro-1H-pyrrolo[2,3-d] intermediates with stereoselective placement of substituents for cyclization to pentacyclic Strychnos alkaloids. The benzyl ester moiety was readily removed by formation of a corresponding nitrile and reduction, thus providing enantioselective syntheses of the tetracyclic
取代的丙烯醛与色氨酸衍生的苄基2-(苄氨基)-3- [3- [2-[([甲氧羰基甲基]吲哚基]吲哚基]]丙酸酯的反应得到四环六氢-1H-吡咯并[2,3-d]中间体取代基的立体选择性放置,以环化成五环马兜铃生物碱。通过形成相应的腈并还原,可以容易地除去苄基酯部分,从而提供四环化合物的对映选择性合成。