Intramolecular Palladium(II)-Mediated Alkoxy Carbonylation as a Route to Functionalized Tetrahydropyrans. Synthesis of the C9−C32 Segment of Phorboxazole A

White, James D.; Kranemann, Christian L.; Kuntiyong, Punlop

doi:10.1021/ol010193a

Cited by 36 publications

(14 citation statements)

References 13 publications

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“…White has also used a palladium( II ) catalysed cyclisation in his construction of the C‐ring of phorboxazole A. After much experimentation he found that the optimal conditions were to use Pd(OAc) 2 in a MeOH/MeCN solvent mix, which furnished a 70 % yield of the C‐ring THP 59 (Scheme ) 43. A similar strategy has also been employed by Kitching in his synthesis of one of the THP rings in the bistramide series of marine metabolites 44…”

Section: Cyclisation Onto Unactivated Carbon–carbon Double Bondsmentioning

confidence: 99%

Strategies for the Formation of Tetrahydropyran Rings in the Synthesis of Natural Products

2006

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This microreview surveys the literature over the last five years with regard to construction of functionalised tetrahydropyran (THP) rings in the context of the synthesis of natural products. The overview given is intended to provide a working knowledge of the area for those who are unfamiliar, and to refresh and remind those who do work in the area of the exciting developments in the field. While the construction of the THP rings in a number of natural products has been reviewed, we have attempted to highlight the different strategies by focusing on two natural products, namely phorboxazole and centrolobine as case studies. Over the last five years, these natural products have become a test bed for new methods for the construction of THP rings. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Section: Cyclisation Onto Unactivated Carbon–carbon Double Bondsmentioning

confidence: 99%

Strategies for the Formation of Tetrahydropyran Rings in the Synthesis of Natural Products

2006

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“…18 Although the method has been demonstrated in the context of tetrahydrofuran synthesis, 19 its application to the construction of tetrahydropyrans has received relatively little attention. 20 In the present case, the outcome leading from a hex-1-en-6-ol to the pentasubstituted tetrahydropyran of 4 was known 21 but many features of the reaction, including its mechanism, were obscure. Two observations were noted in a previous exercise that portended problems for the present study.…”

Section: Synthesis Of the C20-c32 Subunitmentioning

confidence: 72%

Total synthesis of the marine toxin phorboxazole A using palladium(ii)-mediated intramolecular alkoxycarbonylation for tetrahydropyran synthesis

et al. 2012

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The potent antitumor agent phorboxazole A was synthesized from six subunits comprising C1-C2 (115), C3-C8 (98), C9-C19 (74), C20-C32 (52), C33-C41 (84) and C42-C46 (85). Tetrahydropyrans B and C containing cis-2,6-disubstitution were fabricated via palladium(II)-mediated intramolecular alkoxycarbonylation which, in the case of tetrahydropyran C, was carried out with catalytic palladium(II) and p-benzoquinone as the stoichiometric re-oxidant. Tetrahydropyran D was obtained by a stereoselective tin(IV)-catalyzed coupling of a C9 aldehyde with an allylsilane, and the C19-C20 connection was made using a completely stereoselective Wittig-Schlosser (E) olefination. Coupling of the oxazole C32 methyl substituent with the intact C33-C46 δ-lactone 3was accompanied by elimination of the vinyl bromide to a terminal alkyne, but the C32-C33 linkage was implemented successfully with 83 and C33-C41 lactone 84. The C42-C46 segment of the side chain was then appended via Julia-Kocienski olefination. The macrolide portion of phorboxazole A was completed by means of an Ando-Still-Gennari intramolecular (Z)-selective olefination at C2-C3 which required placement of a (dimethoxyphosphinyl)acetate moiety at C24. Final deprotection led to phorboxazole A via a route in which the longest linear sequence is 37 steps and the overall yield is 0.36%.

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“…A palladium-mediated hydroxy-palladation-carbonylation sequence was used in the synthesis of a segment of phorboxazole A [137] The palladium-catalyzed sequential carbonylative esterification was used in the synthesis of macrosphelide A [138] (Scheme 120).…”

Section: Hydroxy-palladation-carbonylationmentioning

confidence: 99%

Catalytic C-C Bond Formation in Natural Products Synthesis: Highlights From The Years 2000 – 2005

Hong¹,

Nimje

2006

COC

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The development of new catalytic reactions for C-C bond formation has played a significant role in natural products synthesis. In this article we review catalytic C-C bond formation with respect to the carbon atoms' hybridization and the products formed. The reactions of unusual substrates and the development of new reaction conditions and catalyst systems are included. This survey highlights the use of catalysts in natural products synthesis during the years 2000-2005.

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Intramolecular Palladium(II)-Mediated Alkoxy Carbonylation as a Route to Functionalized Tetrahydropyrans. Synthesis of the C9−C32 Segment of Phorboxazole A

Cited by 36 publications

References 13 publications

Strategies for the Formation of Tetrahydropyran Rings in the Synthesis of Natural Products

Strategies for the Formation of Tetrahydropyran Rings in the Synthesis of Natural Products

Total synthesis of the marine toxin phorboxazole A using palladium(ii)-mediated intramolecular alkoxycarbonylation for tetrahydropyran synthesis

Catalytic C-C Bond Formation in Natural Products Synthesis: Highlights From The Years 2000 – 2005

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