Concise Synthesis of Complicated Polypropionates through One‐Pot Dissymmetrical Two‐Directional Chain Elongation

Exner, Claudia J.; Turks, Māris; Fonquerne, Freddy; Vogel, Pierre

doi:10.1002/chem.201003264

Cited by 9 publications

(4 citation statements)

References 63 publications

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“…[134] This strategy remains popular, with recent examples including those from the laboratories of Zhang, [135] Metz, [136] Molinski, [137] Blakemore, [138] Nelson, [139] and Vogel. [140] Stockman and coworkers have reported the application of the two-directional approach in both target and diversity oriented synthesis. [141] A skillful recent example is their formal total synthesis of halichlorine, which involved two-directional chain extension of ethyl formate (40) using addition, oxidation, and cross-metathesis reactions (Scheme 22).…”

Section: Independent Reactionsmentioning

confidence: 99%

Multi-Bond Forming Processes in Efficient Synthesis

Green¹,

Sherburn²

2013

Aust. J. Chem.

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An increasing number of synthetic organic chemists are embracing the philosophy of efficiency. Herein we highlight multi-bond forming processes, which form two or more new covalent bonds in a single synthetic operation. Such processes, which have the ability to rapidly increase structural complexity, are preeminent in contemporary synthetic organic chemistry. In this short review we classify, analyse, and contrast contemporary multi-bond forming processes, frame these cutting edge contributions within a historical context, and speculate on likely future developments in the area.

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Section: Independent Reactionsmentioning

confidence: 99%

Multi-Bond Forming Processes in Efficient Synthesis

Green¹,

Sherburn²

2013

Aust. J. Chem.

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“…Derivatization of the two carbinol carbons with (S)-or (R)-αmethoxyphenylacetic acid (MPA) 15 was not successful, presumably due to the steric hindrance exerted by the flanking methyl groups. 16 Then, we applied the previously successful acid hydrolysis to 2. Extraction of the hydrolysate solution with Et 2 O separated βOHAsp (6) in the 6 N HCl layer and Htha (7) in the Et 2 O layer, the yield of the latter being almost quantitative (97%, Scheme 2).…”

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confidence: 99%

“…Methanolysis of 2 with NaOMe afforded carboxylic acid 3 , which was methylated with TMS-diazomethane to give methyl ester 4 . Derivatization of the two carbinol carbons with ( S )- or ( R )-α-methoxyphenylacetic acid (MPA) was not successful, presumably due to the steric hindrance exerted by the flanking methyl groups …”

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confidence: 99%

Complete Stereochemistry and Preliminary Structure–Activity Relationship of Rakicidin A, a Hypoxia-Selective Cytotoxin from Micromonospora sp.

et al. 2014

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The complete stereochemistry of rakicidin A, a hypoxia-selective cytotoxin produced by Micromonospora sp., was unambiguously established by extensive chemical degradation and derivatization studies. During the PGME derivatization-based configurational analysis of 3-hydroxy-2,4,16-trimethylheptadecanoic acid, an irregular Δδ distribution was observed, which necessitated further acylation of the 3-hydroxy group to resolve the inconsistency. A hydrogenated derivative of rakicidin A, its ring-opened product, and two congeners with different alkyl chain lengths were tested for hypoxia-selective cytotoxicity. The results indicated that both the conjugated diene unit and appropriate chain length are essential for the unique activity of rakicidin A.

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“…This furnished 76, a polyketides containing 11 stereogenic centers. As the configuration of the 1-oxydienes 66 and 69 can be either (R) or (S) and since the two successive aldol reactions on the intermediate stereotetrad can used a wide variety of aldehydes under well-chosen conditions, a very large library of polyketides can be prepared applying our method illustrated in Scheme 11 [171,172].…”

Section: Discussionmentioning

confidence: 99%

Expeditious Asymmetric Synthesis of Polypropionates Relying on Sulfur Dioxide-Induced C–C Bond Forming Reactions

Vogel

Gonzalo

2021

Catalysts

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For a long time, the organic chemistry of sulfur dioxide (SO2) consisted of sulfinates that react with carbon electrophiles to generate sulfones. With alkenes and other unsaturated compounds, SO2 generates polymeric materials such as polysulfones. More recently, H-ene, sila-ene and hetero-Diels–Alder reactions of SO2 have been realized under conditions that avoid polymer formation. Sultines resulting from the hetero-Diels–Alder reactions of conjugated dienes and SO2 are formed more rapidly than the corresponding more stable sulfolenes resulting from the cheletropic additions. In the presence of a protic or Lewis acid catalyst, the sultines derived from 1-alkoxydienes are ionized into zwitterionic intermediates bearing 1-alkoxyallylic cation moieties which react with electro-rich alkenes such as enol silyl ethers and allylsilanes with high stereoselectivity. (C–C-bond formation through Umpolung induced by SO2). This produces silyl sulfinates that react with carbon electrophiles to give sulfones (one-pot four component asymmetric synthesis of sulfones), or with Cl2, generating the corresponding sulfonamides that can be reacted in situ with primary and secondary amines (one-pot four component asymmetric synthesis of sulfonamides). Alternatively, Pd-catalyzed desulfinylation generates enantiomerically pure polypropionate stereotriads in one-pot operations. The chirons so obtained are flanked by an ethyl ketone moiety on one side and by a prop-1-en-1-yl carboxylate group on the other. They are ready for two-directional chain elongations, realizing expeditious synthesis of long-chain polypropionates and polyketides. The stereotriads have also been converted into simpler polypropionates such as the cyclohexanone moiety of baconipyrone A and B, Kishi’s stereoheptad unit of rifamycin S, Nicolaou’s C1–C11-fragment and Koert’s C16–CI fragment of apoptolidin A. This has also permitted the first total synthesis of (-)-dolabriferol.

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Concise Synthesis of Complicated Polypropionates through One‐Pot Dissymmetrical Two‐Directional Chain Elongation

Cited by 9 publications

References 63 publications

Multi-Bond Forming Processes in Efficient Synthesis

Multi-Bond Forming Processes in Efficient Synthesis

Complete Stereochemistry and Preliminary Structure–Activity Relationship of Rakicidin A, a Hypoxia-Selective Cytotoxin from Micromonospora sp.

Expeditious Asymmetric Synthesis of Polypropionates Relying on Sulfur Dioxide-Induced C–C Bond Forming Reactions

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