Recent Developments in the Ferrier Rearrangement
01 Nov 2013-European Journal of Organic Chemistry (John Wiley & Sons, Ltd)-Vol. 2013, Iss: 32, pp 7221-7262
TL;DR: A review of recent developments in the use of promoters for the Ferrier rearrangement of O-, N-, C- and S-nucleophiles with glycals can be found in this paper.
About: This article is published in European Journal of Organic Chemistry.The article was published on 2013-11-01. It has received 121 citations till now. The article focuses on the topics: Ferrier rearrangement & Ferrier carbocyclization.
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TL;DR: This Review covers classical approaches to deoxyglycoside synthesis, as well as more recently developed chemistry that aims to control the selectivity of the reaction through rational design of the promoter.
Abstract: Deoxy-sugars often play a critical role in modulating the potency of many bioactive natural products. Accordingly, there has been sustained interest in methods for their synthesis over the past several decades. The focus of much of this work has been on developing new glycosylation reactions that permit the mild and selective construction of deoxyglycosides. This Review covers classical approaches to deoxyglycoside synthesis, as well as more recently developed chemistry that aims to control the selectivity of the reaction through rational design of the promoter. Where relevant, the application of this chemistry to natural product synthesis will also be described.
194 citations
TL;DR: This review highlights the C-glycosylation methods that have been practised in the total synthesis of natural products and pharmaceuticals in the past decade.
Abstract: Chemical C-glycosylation has been well developed to improve stereoselectivity in recent years. Due to its high efficiency to build C-glycosides or O-cyclic compounds, C-glycosylation has found widespread use in the synthesis of biologically active molecules. This review highlights the C-glycosylation methods that have been practised in the total synthesis of natural products and pharmaceuticals in the past decade.
75 citations
TL;DR: In the last few years, considerable progress has been made in the synthesis of C-glycosides as mentioned in this paper, and due to its versatility, C glycosides play a pivotal role in developing novel materials, surfactants and bioactive molecules.
69 citations
TL;DR: In this article, the authors evaluate the fundamental connections between the anomeric effect and a broad variety of O-functional groups and highlight the vast implications of AE for the structure and reactivity of organic O-functionalities.
Abstract: Although carbon is the central element of organic chemistry, oxygen is the central element of stereoelectronic control in organic chemistry. Generally, a molecule with a C–O bond has both a strong donor (a lone pair) and a strong acceptor (e.g., a σ*C–O orbital), a combination that provides opportunities to influence chemical transformations at both ends of the electron demand spectrum. Oxygen is a stereoelectronic chameleon that adapts to the varying situations in radical, cationic, anionic, and metal-mediated transformations. Arguably, the most historically important stereoelectronic effect is the anomeric effect (AE), i.e., the axial preference of acceptor groups at the anomeric position of sugars. Although AE is generally attributed to hyperconjugative interactions of σ-acceptors with a lone pair at oxygen (negative hyperconjugation), recent literature reports suggested alternative explanations. In this context, it is timely to evaluate the fundamental connections between the AE and a broad variety of O-functional groups. Such connections illustrate the general role of hyperconjugation with oxygen lone pairs in reactivity. Lessons from the AE can be used as the conceptual framework for organizing disjointed observations into a logical body of knowledge. In contrast, neglect of hyperconjugation can be deeply misleading as it removes the stereoelectronic cornerstone on which, as we show in this review, the chemistry of organic oxygen functionalities is largely based. As negative hyperconjugation releases the “underutilized” stereoelectronic power of unshared electrons (the lone pairs) for the stabilization of a developing positive charge, the role of orbital interactions increases when the electronic demand is high and molecules distort from their equilibrium geometries. From this perspective, hyperconjugative anomeric interactions play a unique role in guiding reaction design. In this manuscript, we discuss the reactivity of organic O-functionalities, outline variations in the possible hyperconjugative patterns, and showcase the vast implications of AE for the structure and reactivity. On our journey through a variety of O-containing organic functional groups, from textbook to exotic, we will illustrate how this knowledge can predict chemical reactivity and unlock new useful synthetic transformations.
60 citations
TL;DR: This review summarizes the literature on the different transformations of the endo glycals into biologically relevant compounds as well as on the use of glycals as chiral building blocks for the synthesis of various natural products such as aspicilin, reblastatin, diospongins, decytospolides, osmundalactones, paclitaxel, isatisine, d-fagomine, and spliceostatin, reported post 2014.
Abstract: Glycals, 1,2-unsaturated sugar derivatives, are versatile starting materials for the synthesis of natural products and the generation of novel structural features in Diversity Oriented Synthesis (DOS). The versatility of glycals in synthesis emanates, among others, from the presence of the ring oxygen and the enol-ether type unsaturation, the different types of stable conformations they can adopt depending on the nature of the protecting groups present and the ease with which the protecting groups of the three hydroxy groups could be tailored to suite for a desired manipulation. This review summarizes the literature on the different transformations of the endo glycals into biologically relevant compounds such as chromans, thiochromans, chromenes, thiochromenes, peptidomimetics, bridged benzopyrans etc., as well as on the use of glycals as chiral building blocks for the synthesis of various natural products such as aspicilin, reblastatin, diospongins, decytospolides, osmundalactones, paclitaxel, isatisine, D-fagomine, and spliceostatin, reported post 2014.
37 citations
References
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TL;DR: Alkyl 2,3-unsaturated glycopyranosides have been prepared by the Ferrier rearrangement of acetyl protected glycals catalyzed by HClO 4 -SiO 2 as discussed by the authors.
Abstract: Alkyl 2,3-unsaturated glycopyranosides have been prepared by the Ferrier rearrangement of acetyl protected glycals catalyzed by HClO 4 -SiO 2 . Operational simplicity, use of economically convenient catalyst, mild reaction conditions, high yields, short reaction times are the key features of this protocol.
68 citations
TL;DR: Glycals react rapidly with polymethylhydrosiloxane in the presence of a catalytic amount of molecular iodine under mild conditions to afford the corresponding 3,6-dihydropyran derivatives in excellent yields.
68 citations
TL;DR: D-Glycals react smoothly with a variety of alcohols, phenols and hydroxy α-amino acids in the presence of 5 mol% dysprosium triflate immobilized in 1-butyl-3-methylimidazolium hexafluorophosphate under mild reaction conditions to afford the corresponding 2,3-unsaturated glycopyranosides in excellent yields with high α-selectivity.
Abstract: D-Glycals react smoothly with a variety of alcohols, phenols and hydroxy α-amino acids in the presence of 5 mol% dysprosium triflate immobilized in 1-butyl-3-methylimidazolium hexafluorophosphate under mild reaction conditions to afford the corresponding 2,3-unsaturated glycopyranosides in excellent yields with high α-selectivity. The catalyst immobilized in ionic liquids was recycled in subsequent reactions without any apparent loss of activity.
67 citations
TL;DR: In this paper, a novel glycal-based O-glycosylation reaction, in which the substrates are not only peracetyl glycals but also perbenzyl glucals to afford the corresponding 2,3-unsaturated-O-glucosides via Ferrier rearrangement, was developed.
66 citations
TL;DR: In this article, it was shown that triacetyl glucal can be converted to 6-O-triphenylmethyl ether or 6 O-benzoyl ester to promote solubility in chloroform, and the derivatives are oxidized in that solvent in 12 h or less.
Abstract: Whereas the pseudo-axial 3-hydroxyl group of allal derivatives is known to be inert to manganese dioxide oxidation, the equatorial counterpart in glucal derivatives is shown to be readily oxidized. Thus glucal is converted to the 6-O-triphenylmethyl ether or 6-O-benzoyl ester to promote solubility in chloroform, and the derivatives are oxidized in that solvent in 12 h or less.Acetonation of glucal is readily accomplished in 45 min using 2,2-dimethoxypropane and p-toluenesulfonic acid in dimethylformamide; the product may be oxidized directly either with manganese dioxide or dipyridine chromium oxide. Thus it is possible to obtain 1–3-g quantities of the crystalline acetonated enone from triacetyl glucal (via deacetylation, acetonation, and oxidation) in 3–4 h.If the acetonation medium stands for 2 h methyl 2,3-dideoxy-4,6-O-isopropylidene-α-D-erythro-hex-2-enopyranoside is obtained. The mechanism of its formation in the reaction medium is discussed.
64 citations