Asymmetric catalytic dihydroxylation of alkenes on polymer support: Scope and limitation

Lohray, B. B.; Thomas, A.; Chittari, Pabba; Ahuja, Jaimala R.; Dhal, Pradeep K.

doi:10.1016/s0040-4039(00)79119-2

Cited by 62 publications

(13 citation statements)

References 9 publications

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“…The use of quinine and quinidine on a polystyrenic support has also been reported by Lohray and coworkers 26 . They performed AD using the homopolymer 18 and the copolymers of a QD derivative with styrene, 19, and 4-phenylstyrene, 20.…”

Section: Role Of the Polymeric Supportsupporting

confidence: 60%

Insoluble Polymer-Bound (IPB) Approach to the Catalytic Asymmetric Dihydroxylation of Alkenes

Salvadori¹,

Pini²,

Petri³

1999

Synlett

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Asymmetric dihydroxylation induced by Insoluble Polymer-Bound (IPB approach) Cinchona alkaloid derivatives is reviewed. Reactivities and enantioselectivities comparable to those achieved with the soluble counterparts are obtained with polymers having structural properties compatible with the reaction conditions. By using a highly efficient polymer, olefins with different structures can be dihydroxylated at a synthetically useful level of enantioselectivity. Handling and recovery of the catalyst is very easy; recycling is performed with a small amount of metal.

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Section: Role Of the Polymeric Supportsupporting

confidence: 60%

Insoluble Polymer-Bound (IPB) Approach to the Catalytic Asymmetric Dihydroxylation of Alkenes

Salvadori¹,

Pini²,

Petri³

1999

Synlett

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“…3 Our interest in this topic goes back several years, 4,5 when a significant paper by Kim and Sharpless 6 was also noted. In addition to our work, [7][8][9][10] other groups reported results obtained using insoluble organic polymeric supports, [11][12][13][14][15] but in some cases it is not clear if the reaction actually occurred in the heterogeneous phase. Indeed, using one of the catalytic systems prepared by a previously described procedure, 12 but after a continuous extraction with methanol, we obtained 16 considerably lower enantioselectivity than achieved with the crude polymer.…”

mentioning

confidence: 51%

Catalytic asymmetric dihydroxylation of alkenes induced by polymeric chiral ligands

et al. 1999

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“…In addition to solution chemistry, the ligands can also be supported on a polymer [134][135][136][137][138][139][140][141][142][143], including polystyrene [144], mesoporous molecular sieve [145], ion exchange resin [146,147], macroporous resins [148], silica [149,150], and amorphous silica gel [145,151]. In addition to solution chemistry, the ligands can also be supported on a polymer [134][135][136][137][138][139][140][141][142][143], including polystyrene [144], mesoporous molecular sieve [145], ion exchange resin [146,147], macroporous resins [148], silica [149,150], and amorphous silica gel [145,151].…”

Section: Variationsmentioning

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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Asymmetric catalytic dihydroxylation of alkenes on polymer support: Scope and limitation

Cited by 62 publications

References 9 publications

Insoluble Polymer-Bound (IPB) Approach to the Catalytic Asymmetric Dihydroxylation of Alkenes

Insoluble Polymer-Bound (IPB) Approach to the Catalytic Asymmetric Dihydroxylation of Alkenes

Catalytic asymmetric dihydroxylation of alkenes induced by polymeric chiral ligands

Cinchona Alkaloids as Chiral Ligands in Asymmetric Oxidations

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