Asymmetric synthesis of l-DOPA and (R)-selegiline via, OsO4-catalyzed asymmetric dihydroxylation

Sayyed, Iliyas Ali; Sudalai, Arumugam

doi:10.1016/j.tetasy.2004.08.007

Cited by 60 publications

(39 citation statements)

References 25 publications

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“…However, this chemical process passes through several steps, requires an expensive metal catalyst, and shows a poor conversion rate and a low enantiomeric excess (Hans-Ulrich Blaser, 2004;Sayyed and Sudalai, 2004;Vald et al, 2004). Therefore, research has focused on developing alternative l-DOPA synthesis to economize production cost and improve conversion rate and enantioselectivity; microbiological method by microorganism and enzymatic method by isolated tyrosinase.…”

Section: Introductionmentioning

confidence: 99%

Electroenzymatic synthesis of l-DOPA

Min

Park

Yoo

2010

Journal of Biotechnology

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Section: Introductionmentioning

confidence: 99%

Electroenzymatic synthesis of l-DOPA

Min

Park

Yoo

2010

Journal of Biotechnology

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“…The change in regiocontrol exerted by an aryl group on the reaction is illustrated in a synthesis of L-DOPA (31) (Scheme 3.33) [349].…”

Section: Asymmetric Dihydroxylation Of Alkenes J55mentioning

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 chemical synthesis of SAA suffers from intractable enantioselectivities for large-scale production [11]. An alternative route for SAA production was developed previously in our laboratory via metabolic engineering of Escherichia coli [12, 13] (Fig.…”

Section: Introductionmentioning

confidence: 99%

Chromosome engineering of Escherichia coli for constitutive production of salvianic acid A

et al. 2017

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BackgroundSalvianic acid A (SAA), a valuable natural product from herbal plant Salvia miltiorrhiza, exhibits excellent antioxidant activities on food industries and efficacious therapeutic potential on cardiovascular diseases. Recently, production of SAA in engineered Escherichia coli was established via the artificial biosynthetic pathway of SAA on the multiple plasmids in our previous work. However, the plasmid-mediated system required to supplement expensive inducers and antibiotics during the fermentation process, restricting scale-up production of SAA. Microbial cell factory would be an attractive approach for constitutive production of SAA by chromosome engineering.ResultsThe limited enzymatic reactions in SAA biosynthetic pathway from glucose were grouped into three modules, which were sequentially integrated into chromosome of engineered E. coli by λ Red homologous recombination method. With starting strain E. coli BAK5, in which the ptsG, pykF, pykA, pheA and tyrR genes were previously deleted, chassis strain BAK11 was constructed for constitutive production of precursor l-tyrosine by replacing the 17.7-kb mao-paa cluster with module 1 (PlacUV5-aroG fbr-tyrA fbr-aroE) and the lacI gene with module 2 (Ptrc-glk-tktA-ppsA). The synthetic 5tacs promoter demonstrated the optimal strength to drive the expression of hpaBC-d-ldh Y52A in module 3, which then was inserted at the position between nupG and speC on the chromosome of strain BAK11. The final strain BKD13 produced 5.6 g/L of SAA by fed-batch fermentation in 60 h from glucose without any antibiotics and inducers supplemented.ConclusionsThe plasmid-free and inducer-free strain for SAA production was developed by targeted integration of the constitutive expression of SAA biosynthetic genes into E. coli chromosome. Our work provides the industrial potential for constitutive production of SAA by the indel microbial cell factory and also sets an example of further producing other valuable natural and unnatural products.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-017-0700-2) contains supplementary material, which is available to authorized users.

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Asymmetric synthesis of l-DOPA and (R)-selegiline via, OsO4-catalyzed asymmetric dihydroxylation

Cited by 60 publications

References 25 publications

Electroenzymatic synthesis of l-DOPA

Electroenzymatic synthesis of l-DOPA

Cinchona Alkaloids as Chiral Ligands in Asymmetric Oxidations

Chromosome engineering of Escherichia coli for constitutive production of salvianic acid A

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