Total synthesis of the marine toxin phorboxazole A using palladium(ii)-mediated intramolecular alkoxycarbonylation for tetrahydropyran synthesis
作者:Punlop Kuntiyong、Tae Hee Lee、Christian L. Kranemann、James D. White
DOI:10.1039/c2ob25766a
日期:——
side chain was then appended via Julia–Kocienski olefination. The macrolide portion of phorboxazole A was completed by means of an Ando–Still–Gennari intramolecular (Z)-selective olefination at C2–C3 which required placement of a (dimethoxyphosphinyl)acetate moiety at C24. Final deprotection led to phorboxazole A via a route in which the longest linear sequence is 37 steps and the overall yield is
有效的抗肿瘤药佛洛他唑A由六个亚基合成而成,包括C1-C2(115),C3-C8(98),C9-C19(74),C20-C32(52),C33-C41(84)和C42-C46 (85)。通过钯(II)介导的分子内烷氧基羰基化反应制备了含有顺式-2,6-二取代基的四氢吡喃B和C ,在四氢吡喃C的情况下,四氢吡喃B和C用催化钯(II)和对-苯醌作为化学计量的-氧化剂。四氢吡喃d用立体选择性锡(获得IV)催化的C9醛与烯丙基硅烷的偶联,以及C19–C20连接是使用完全立体选择性的Wittig–Schlosser(E)烯烃进行的。恶唑C32甲基取代基与完整的C33–C46δ-内酯3的偶联伴随着乙烯基溴消除至末端炔烃的产生,但是C32–C33的连接成功地通过83和C33–C41内酯84实施。然后,侧链的C42–C46链段通过Julia–Kocienski烯烃附加。佛波唑A的大环内酯部分通过Ando–