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: Substitution reactions of allylic acetates and allylic alcohols by a variety of nucleophiles proceed smoothly in the presence of lithium perchlorate in ether, providing a convenient alternative to transition metal catalyzed methods as discussed by the authors.
Abstract: Substitution reactions of allylic acetates and allylic alcohols by a variety of nucleophiles proceed smoothly in the presence of lithium perchlorate in ether, providing a convenient alternative to transition metal catalyzed methods
40 citations
TL;DR: In this article, structural evidence for the existence of avinylogous anomeric effect is presented for a series of 4H-4-benzotriazolyl-2,6-diarylpyrans 1a,b and for their benzo-fused derivatives 2−5 and nitrogen analogue 6.
40 citations
TL;DR: The carbon-Ferrier rearrangement as mentioned in this paper is the reaction of appropriately functionalised glycals, with a variety of carbon nucleophiles such as allyltrimethylsilanes, alkynyl trimethylsiles, silyl cyanides etc.
Abstract: The carbon-Ferrier rearrangement is the reaction of appropriately functionalised glycals, with a variety of carbon nucleophiles such as allyltrimethylsilanes, alkynyltrimethylsilanes, silyl cyanides etc. involving the corresponding nucleophilic addition at the anomeric carbon with concomitant loss of a substituent at C-3. This leads to double bond migration to give 2,3unsaturated sugars which act as useful chiral substrates for further manipulations in organic synthesis.
39 citations
TL;DR: Anhydrous hydrogen iodide is generated in situ by the reaction of solid iodine and a thiol and has been employed for the efficient preparation of alpha-glycosyl iodides and vicinal iodohydrins from the corresponding Glycosyl acetates and epoxides, respectively, and for Ferrier glycosylation of alcohols and thiols.
39 citations
TL;DR: This review places special emphasis on two aspects of exo-glycals including general methods of preparation and synthetic applications for making biologically important molecules, namely C-glycosides, enzyme inhibitors and bioactive natural products.
Abstract: It is well known that carbohydrates play an indispensable role in a variety of essential biological activities, such as cell-cell adhesion, bacteria and virus infections, and tumor metastasis. Among an increasing number of sugars and sugar mimetics that have been designed and synthesized for the purpose of drug discovery, C-glycosides are considered to be one of the best choices on account of their stability and resemblance as they differ from normal glycosides only in glycosidic linkages. exo-Glycals are unsaturated sugars that have a double bond attached to the anomeric center outside the sugar ring. These carbohydrate molecules are useful for the synthesis of C-glycosides and compounds containing quaternary carbons, provided that the olefin can be properly reduced or functionalized. This review places special emphasis on two aspects of exo-glycals including general methods of preparation and synthetic applications for making biologically important molecules. The first half discusses the methods of addition/elimination and Ramburg-Backlund rearrangement that offer many beneficial features including a wide range of double bond substitutions, limited reaction steps, easy operation and good overall yields. The rest of the article demonstrates a number of synthetic studies using exoglycals as the starting materials. The target molecules can be categorized into three groups, namely C-glycosides, enzyme inhibitors and bioactive natural products.
39 citations