The hydrophobic sidechain of scyphostatin was synthesized by a convergent synthetic pathway. The key reactions were the enzymatic asymmetric acetylation of a meso-diol, construction of the C12′–C13′ trisubstituted E-olefin moiety by Negishi coupling, and construction of the (2′E,4′E ,E,6′E)-triene moiety by Horner–Wadsworth–Emmons olefination.
Synthesis (and Alternative Proof of Configuration) of the Scyphostatin C(1‘)−C(20‘) Trienoyl Fragment
作者:Thomas R. Hoye、Manomi A. Tennakoon
DOI:10.1021/ol0058386
日期:2000.5.1
[GRAPHICS]Each of four diastereomers of structure 2, corresponding to the lipophilic side chain of scyphostatin (1), were prepared. Careful analysis of their NMR spectral data and comparison with those of the natural product corroborates the recently reported (Org. Lett. 2000, 2, 505) stereochemical assignment. A strategy for the stereoselective synthesis of 2 has been achieved.
Total synthesis of (+)-scyphostatin featuring an enantioselective and highly efficient route to the side-chain via Zr-catalyzed asymmetric carboalumination of alkenes (ZACA)
(+)-Scyphostatin (1) was synthesized via (i) construction of a side-chain 3b of > or = 98% purity in 19% yield in eleven steps featuring ZACAreaction, Negishi coupling, and HWE olefination, (ii) an asymmetric synthesis of a fully protected core 4 from 10a, and (iii) a three-step assembly of 1 in 42% yield.
An Efficient and General Method for the Synthesis ofα,ω-Difunctional Reduced Polypropionates by Zr-Catalyzed Asymmetric Carboalumination: Synthesis of the Scyphostatin Side Chain