Synthesis of Discodermolide Subunits by S<sub>E</sub>2‘ Addition of Nonracemic Allenylstannanes to Aldehydes
作者:James A. Marshall、Zhi-Hui Lu、Brian A. Johns
DOI:10.1021/jo971900+
日期:1998.2.1
and reduction of the double bond leading to the (E)-allylic alcohol 6. Sharpless epoxidation and subsequent addition of Me(2)CuCNLi(2) yielded the syn,syn,syn,anti stereopentad, diol 8. Protection of the secondary alcohol and oxidation of the primary gave aldehyde 12, which was treated with the alpha-bromo allylsilane 13 and CrCl(2), followed by NaH to effect elimination to the diene 15. A similar
从(S)-3-[(叔丁基二甲基甲硅烷基)氧基] -2-甲基丙醛((S)-1)和对映体富集的烯丙斯坦酮(P)制备了免疫抑制剂二糖单核苷酸的三个亚基15、29和34 -2a,(P)-2b和(P)-31。到达15的途径涉及BF(3)促进将金刚烷(P)-2a添加到醛(S)-1中,从而以97%的产率提供了顺式,顺式-同炔丙基醇加合物3。衍生的对甲氧基亚苄基乙缩醛5用Red-Al处理,以实现新戊酸酯的裂解和双键的还原,从而导致(E)-烯丙基醇6。急剧的环氧化和随后的Me(2)CuCNLi(2)添加得到顺式,顺式,顺式,反立体五醇,二醇8。保护仲醇并氧化伯,得到醛12,将其用α-溴烯丙基硅烷13和CrCl(2)处理,然后用NaH消除二烯15。采用类似的步骤制备醛29。在这种情况下,通过将Sn-1生成的烯丙基铟试剂处理,将其转化为反正同炔丙醇20。原位于烯丙基锡烷(P)-2b和InBr(3)。按照上述顺序