Retrosynthetic and synthetic chemistry on amphotericin B. Synthesis of C(1)–C(20) and C(21)–C(38) fragments and construction of the 38-membered macrocycle
作者:K. C. Nicolaou、T. K. Chakraborty、R. A. Daines、N. S. Simpkins
DOI:10.1039/c39860000413
日期:——
For the first time, amphotericinB (I) has been successfully derivatized and degraded to intermediates that have been converted into compounds (II)[C(1)–C(20) fragment] and (III)[C(21)–C(38) fragment], projected as major key intermediates for a total synthesis; methods have been developed for the coupling of fragments (II) and (III) to give the ketophosphonate–aldehyde (28) and for the cyclization
The synthesis of three 9,11-dideoxyprostaglandins in which the cyclopentane moiety is replaced by a six-membered ring, is described. Starting from phthalaldehydic acid (1) the aromatic PG-analogue, 7-[2-(3-hydroxy-(E)-1-octenyl)phenyl]heptanoic acid (9), was prepared in 7 steps in 49% overall yield. The cis-substituted cyclohexane PG-analogue, ethyl 7-[cis-2-(3-hydroxy-(E)-1-octenyl)cyclohexyl]heptanoate
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.
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.