The Osmium Tetroxide-catalyzed Hydroxylation of Furan-Maleic Anhydride Adducts<sup>1</sup>

Daniels, Ralph; Fischer, J. L.

doi:10.1021/jo01037a010

Cited by 45 publications

(22 citation statements)

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“…Osmium-catalyzed bis-hydroxylation of olefin 4 was carried out similar to literature procedure to afford diol 5 in 79% isolated yield. [23] Chemoselective protection of diol 5 with 4,4 -dimethoxytrityl chloride in pyridine followed by treatment with acetic anhydride without isolation of the intermediate gave the acetoxy protected compound 7 as colorless amorphous compound in 74% yield. Loading of universal linker molecule 7 to amino-derivatized polymeric solid support was carried our using HBTU as coupling activator to give the appropriate loading (200 µmol/g).…”

Section: Synthesis Of Universal Linker and Loading To Solid Supportmentioning

confidence: 99%

A Novel Universal Linker for Efficient Synthesis of Phosphorothioate Oligonucleotides

Wang

Olsen

Ravikumar

2007

Nucleosides, Nucleotides and Nucleic Acids

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A versatile and conformationally preorganized universal linker molecule is reported here for efficient synthesis of phosphorothioate oligonucleotides. With respect to nucleoside loaded support, comparable yield and quality based on ion-pair LC-MS are obtained for both deoxy and 2'-O-methoxyethyl modified phosphorothioate oligonucleotides. No 3'-phosphate or phosphorothioate monoester or any modification of universal molecule still attached to oligonucleotide was observed. [structure: see text]

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Section: Synthesis Of Universal Linker and Loading To Solid Supportmentioning

confidence: 99%

A Novel Universal Linker for Efficient Synthesis of Phosphorothioate Oligonucleotides

Wang

Olsen

Ravikumar

2007

Nucleosides, Nucleotides and Nucleic Acids

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“…Attack by hydroxide ion from the endo-face of 33 is certainly hindered, so attack at the silicon centre seems a viable alternative pathway (Scheme 6).Attempted cleavage of the lactone (32) with a variety of acidic reagents failed to provide the required hydroxyacid. The new signal was assigned to the endo alcohol(34). The acids used in our study were methanesulphonic, p-toluenesulphonic and trifluoroacetic.…”

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confidence: 92%

Development of Methodology Based on the Use of the 7-Oxabicyclo[2.2.1]heptanyl System for the Preparation of carbohydrate Derivatives

Ager¹,

East²

1994

HETEROCYCLES

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The 7-oxabicyclo:2,?,!jheptany! system provides 2 rapid entry to carbohydrate derivatives in a stereoselective manner by virtue of the rigid framework. The formation of this bicyclic system through a Diels-Alder reaction of furan with a number of dienophiles is influenced by the substitution on the dienophile. Use of an anion stabilising group as a carbonyl equivalent has previously led to a ring opening reaction of the bicyclic system. However, anion chemistry can be used to functionalise the bicyclic system, and used for the introduction of a hydroxy group that allows, in turn, a method for the preparation of hexose derivatives.As part of our work to investigate the reactions of the 7-oxabicyclo[2.2.l]heptanyl system for the preparation of tetrahydrofuran derivative^,^ it came to our attention that, as others have ~e e n ,~.~ this bicyclic system has great potential for the synthesis of carbohydrate derivatives, other natural products, and their a n a~o~u e s~~' -~ but not all of the latent functionality was being put to good use.We, therefore, set out to investigate the use of the 7-oxabicyclo[2.2.l]heptanyl system for the preparation of carbohydrate analogues, and to augment the chemistry of these systems to allow the preparation of hexose derivatives. The pivotal compound to our strategy became the ketone (I), as used by Vogel, because of the flexibility available for the introduction of functionality at carbon atoms C-5. and -6.3353'0 * Dedicated to Professor Alan Katritzky on the occasion of his 65th birthday.

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“…This chapter discusses the uses of these alkaloids as chiral ligands in asymmetric oxidation reactions. This steric effect is amplified in cyclic substrates [39,40]. The formation of an intermediate cyclic ester accounts for the cis-stereochemistry [21, 23-32] as reaction occurs on the least hindered face of the alkene [21,30,[33][34][35][36][37][38].…”

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confidence: 99%

“…The formation of an intermediate cyclic ester accounts for the cis-stereochemistry [21, 23-32] as reaction occurs on the least hindered face of the alkene [21,30,[33][34][35][36][37][38]. This steric effect is amplified in cyclic substrates [39,40]. The reaction conditions have to be carefully controlled to avoid oxidative cleavage of the diol product [28].…”

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confidence: 99%

Cinchona Alkaloids as Chiral Ligands in Asymmetric Oxidations

Ager¹

2009

Cinchona Alkaloids in Synthesis and Catalysis

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For oxidation reactions, the cinchona alkaloids have been mainly employed to control the osmium-catalyzed conversion of an alkene to give a 1,2-diol or vicinal functionalized alcohol. As these are important asymmetric reactions, they have been the subject of a number of reviews [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. This chapter discusses the uses of these alkaloids as chiral ligands in asymmetric oxidation reactions. Oxidation reactions where an alkaloid is used in a phase-transfer sense are discussed in Chapter 5.The use of osmium tetroxide for the conversion of an alkene to a 1,2-diol is a wellestablished reaction [19][20][21][22]. The formation of an intermediate cyclic ester accounts for the cis-stereochemistry [21, 23-32] as reaction occurs on the least hindered face of the alkene [21,30,[33][34][35][36][37][38]. This steric effect is amplified in cyclic substrates [39,40]. The reaction conditions have to be carefully controlled to avoid oxidative cleavage of the diol product [28].There is a marked rate acceleration in the presence of a tertiary amine or pyridine [19,41]. This finding provided the background for the asymmetric dihydroxylation (AD) and, later, the asymmetric aminohydroxylation (AA) reactions as it is this ligand acceleration effect (LAE) that ensures the reaction pathway involving the ligand.The use of a cooxidant can reduce the amount of osmium required for a complete reaction of an alkene from stoichiometric to catalytic; some examples of oxidants that can achieve this are peroxides [20,22,35,37,[42][43][44] including hydrogen peroxide [20,42], chlorates [45], periodate [46,47], hypochlorite [48], N-methylmorpholine-N-oxide (NMMO) [22,34,35,37,49], potassium ferricyanide [50,51], and even air [52,53].Stereoselection for the OsO 4 reactions itself can also be observed when a directing group is adjacent to the alkene, such as in an allyl alcohol. An empirical rule has been devised, where the reagent approaches from the face opposite to the preexisting oxygen functionality. Although the hydroxy group may be protected, the presence of an acyl group reduces stereoselectivity. cis-Alkenes afford better selectivity

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The Osmium Tetroxide-catalyzed Hydroxylation of Furan-Maleic Anhydride Adducts¹

Cited by 45 publications

References 0 publications

A Novel Universal Linker for Efficient Synthesis of Phosphorothioate Oligonucleotides

A Novel Universal Linker for Efficient Synthesis of Phosphorothioate Oligonucleotides

Development of Methodology Based on the Use of the 7-Oxabicyclo[2.2.1]heptanyl System for the Preparation of carbohydrate Derivatives

Cinchona Alkaloids as Chiral Ligands in Asymmetric Oxidations

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The Osmium Tetroxide-catalyzed Hydroxylation of Furan-Maleic Anhydride Adducts1

Cited by 45 publications

References 0 publications

A Novel Universal Linker for Efficient Synthesis of Phosphorothioate Oligonucleotides

A Novel Universal Linker for Efficient Synthesis of Phosphorothioate Oligonucleotides

Development of Methodology Based on the Use of the 7-Oxabicyclo[2.2.1]heptanyl System for the Preparation of carbohydrate Derivatives

Cinchona Alkaloids as Chiral Ligands in Asymmetric Oxidations

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The Osmium Tetroxide-catalyzed Hydroxylation of Furan-Maleic Anhydride Adducts¹