Total Synthesis of (+)-Phorboxazole A Exploiting the Petasis−Ferrier Rearrangement
作者:Amos B. Smith、Kevin P. Minbiole、Patrick R. Verhoest、Michael Schelhaas
DOI:10.1021/ja011604l
日期:2001.11.1
convergent, stereocontrolled total synthesis of the potent antiproliferative agent (+)-phorboxazole A (1) has been achieved. Highlights of the synthesis include: modified Petasis-Ferrier rearrangements for assembly of both the C(11-15) and C(22-26) cis-tetrahydropyran rings; extension of the Julia olefination to the synthesis of enol ethers; the design, synthesis, and application of a novel bifunctional
(+)-Phorboxazole A Synthetic Studies. A Highly Convergent, Second Generation Total Synthesis of (+)-Phorboxazole A
作者:Amos B. Smith、Thomas M. Razler、Jeffrey P. Ciavarri、Tomoyasu Hirose、Tomoyasu Ishikawa
DOI:10.1021/ol051584i
日期:2005.9.1
[structure: see text] A second generation totalsynthesis of the potentantitumoragent (+)-phorboxazole A (1) has been achieved. The cornerstone of this approach comprises a more convergent strategy, involving late-stage Stille union of a fully elaborated C(1-28) macrocycle with a C(29-46) side chain. The second generation synthesis entails the longest linear sequence of 24 steps, with an overall
Phorboxazole B synthetic studies: construction of C(1–32) and C(33–46) subtargets
作者:Ian Paterson、Alan Steven、Chris A. Luckhurst
DOI:10.1039/b407240e
日期:——
The convergent syntheses of the C(1â32) and C(33â46) domains of phorboxazole B are described. An iterative cyclocondensation strategy exploited the Jacobsen hetero-DielsâAlder (HDA) reaction as a platform for the synthesis of both the C(5â9) and C(11â15) tetrahydropyran rings. The use of 2-silyloxydiene coupling partners bearing an increasing resemblance to the phorboxazole skeleton was found to lead to a reduction in diastereoselectivity, however, in the case of the C(11â15) ring. The coupling of aldehyde 21 and 2-silyloxydiene 20 by this route provided a C(1â32) fragment which was elaborated to the macrolide core of phorboxazole B. The synthesis of the C(33â46) domain involved a NozakiâKishi coupling of aldehyde 31 and vinyl iodide 39. The syntheses of 31 and 39 were highly diastereoselective: an Evans [Cu(Ph-pybox)](SbF6)2-catalysed Mukaiyama aldol reaction formed the cornerstone of the synthesis of 31 whilst a NagaoâFujita acetate aldol reaction provided a convenient means of installing the sole stereogenic centre of 39.
Phorboxazole Synthetic Studies. 1. Construction of a C(3−19) Subtarget Exploiting an Extension of the Petasis−Ferrier Rearrangement
作者:Amos B. Smith、Patrick R. Verhoest、Kevin P. Minbiole、John J. Lim
DOI:10.1021/ol990830l
日期:1999.9.1
text] In this, the first of two letters, we outline our overall strategy for the totalsynthesis of phorboxazoles A (1) and B (2), rare oxazole-containing macrolides possessing extraordinary antimitotic activity, and describe the assembly of a C(3-19) subtarget (-)-5 for the totalsynthesis of phorboxazole A. The synthesis of (-)-5 was achieved in 15 linear steps (12% overall yield), exploiting a modification
Synthetic studies directed toward the phorboxazoles: preparation of the C3–C15 bisoxane segment and two stereoisomers
作者:Patrick B. Greer、William A. Donaldson
DOI:10.1016/s0040-4020(02)00613-0
日期:2002.7
A synthetic approach to the C3-C15 segment of the cytotoxic marine metabolite phorboxazoles is described. This segment consists of a methylene linked bisoxane structure. The first pyran ring was constructed by a Lewis acid catalyzed diene-aldehyde cyclo-condensation. The beta-C-glucoside substitution pattern of this ring was established by a stereoselective allylation. Ozonolysis of vinyl group and enantioselective allylation of the racemic aldehyde generated two separable homoallylic alcohols (-)-22 and (+)-23. The Mosher's esters of each alcohol were determined to be >90% de. Reaction of (-)-22 with acryloyl chloride, followed by ring closing metathesis gave the dihydro-2-pyrone target (-)-5. Mitsunobu inversion of (+)-23 with p-nitrobenzoic acid, hydrolysis, and esterification with acryloyl chloride and ring closing metathesis gave pseudoenantiomeric segment (+)-6. (C) 2002 Published by Elsevier Science Ltd.