New Syntheses of E7389 C14-C35 and Halichondrin C14-C38 Building Blocks: Double-Inversion Approach
New Syntheses of E7389 C14-C35 and Halichondrin C14-C38 Building Blocks: Double-Inversion Approach
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DOI：
10.1021/ja9058475
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发表时间：
2009-11-04
影响因子：
15
通讯作者：
Kishi, Yoshito
中科院分区：
文献类型：
--
作者：
Kim, Dae-Shik;Dong, Cheng-Guo;Kishi, Yoshito
With sequential use of catalytic asymmetric Cr-mediated coupling reactions, E7389 C14-C35 and halichondrin C14-C38 building blocks have been stereoselectively synthesized. The C19-C20 bond is first formed via the catalytic asymmetric Ni/Cr-mediated coupling, i.e., 8 + 9 -> 10 (90%; dr = 22:1), in which vinyl iodide 8 is used as the limiting substrate. The C23-C24 bond is then formed via the catalytic asymmetric Co/Cr-mediated coupling, i.e., 13 + 14 -> 4 (82%; or = 22:1), in which the alkyl-iodide bond in 14 is selectively activated over the vinyl-iodide bond. The catalytic asymmetric Ni/Cr-mediated reaction is employed to couple C14-C26 segment 19 with E7389 C27-C35 segment 20 (91%; dr = >55:1). In this synthesis, the C23-0 bond is stereoselectively constructed via a double-inversion process, i.e., 21 -> 22, to furnish E7389 C14-C35 building block 22 in 84% yield. The same synthetic sequence has been employed to synthesize halichondrin C14-C38 building block 18b, i.e., 16a + 19 -> 18b.
