Microbial oxidation of chloroaromatics in the enantiodivergent synthesis of pyrrolizidine alkaloids: trihydroxyheliotridanes

Hudlický, Tomáš; Luna, Héctor; Price, John D.; Fan, Rulin

doi:10.1021/jo00302a037

Cited by 170 publications

(62 citation statements)

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“…The 2,3-cis-and 2,3-trans-stereochemistries were readily established from 1 H-NMR analyses. As shown in Table 2, the 2,3-cis-aziridines 14a-g show the JH 2,3 value (Jϭ7.3-7.8 Hz, entries 1-7) larger than that of the corresponding 2,3-trans-isomers 15a-g (Jϭ4.0-5.1 Hz, entries [8][9][10][11][12][13][14]. The data are in good agreement with 1 H-NMR data for related compounds.…”

Section: Palladium(0)-catalyzed 23-cis-selective Aziridination Reactsupporting

confidence: 75%

“…[2][3][4][5][6][7][8] Particularly, aziridines bearing an alkenyl [9][10][11][12][13][14] or ethynyl group [15][16][17][18] on one of the aziridine-ring carbon atoms have proven to be extremely useful intermediates for asymmetric preparation of such compounds as alkaloids, 9,10) b-lactams, [11][12][13] vinylglycines, 14) amino allenes, 15,16) amino alcohols, 17,18) and (E)-alkene dipeptide isosteres. [19][20][21][22] Although some stereoselective syntheses of enantiomerically pure 2-alkenylaziridines have been reported, most of the reported methods consist of two processes, formation of the aziridine ring and construction of the olefinic moiety, via several steps.…”

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confidence: 99%

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Stereodivergent Synthesis of Chiral 2-Alkenylaziridines: Palladium(0)-Catalyzed 2,3-cis-Selective Aziridination and Base-Mediated 2,3-trans-Selective Aziridination

Ohno

Takemoto

Fujii

et al. 2004

CHEMICAL & PHARMACEUTICAL BULLETIN

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Chiral N-activated aziridines are widely used as building blocks for the asymmetric synthesis of biologically and synthetically important compounds. [2][3][4][5][6][7][8] Particularly, aziridines bearing an alkenyl [9][10][11][12][13][14] or ethynyl group [15][16][17][18] on one of the aziridine-ring carbon atoms have proven to be extremely useful intermediates for asymmetric preparation of such compounds as alkaloids, 9,10) b-lactams, 11-13) vinylglycines, 14) amino allenes, 15,16) amino alcohols, 17,18) and (E)-alkene dipeptide isosteres. [19][20][21][22] Although some stereoselective syntheses of enantiomerically pure 2-alkenylaziridines have been reported, most of the reported methods consist of two processes, formation of the aziridine ring and construction of the olefinic moiety, via several steps.In connection with our program directed toward synthesis of (E)-alkene dipeptide isosteres, [19][20][21] we required an efficient stereoselective synthetic method of chiral 2-alkenylaziridines. Recently, we reported a palladium(0)-catalyzed aziridination of allylic carbonates 1a preferentially affording thermodynamically more stable 2,3-cis-2-vinylaziridines 2 over the corresponding trans isomers 3 in good selectivities (2 : 3ϭ94 : 6-98 : 2, Eq. 1).23) In these reaction conditions, the palladium catalyst not only converts the carbonates 1a into the aziridines 2 and 3 but also equilibrates the isomeric mixtures of 2 and 3 via p-allylpalladium(II) intermediates A. 20,21) In contrast, base-mediated intramolecular amination of mesylates 1b with NaH in DMF produces mixtures of 2 and 3 in variable ratios (2,3-cis : transϭ8 : 92-51 : 49) depending on the steric bulkiness of the alkyl substituent R 1 (Eq. 2).23-25) Interestingly, while (Z)-allylic carbonates 4a provide 2,3-cis-2-vinylaziridines 2 stereoselectively (2 : 3ϭ 94 : 6-97 : 3) under the palladium(0)-catalyzed cyclization conditions (Eq. 3), sodium hydride-mediated cyclization of (Z)-allylic mesylates 4b affords 3-pyrrolines 5 as the sole isolable product (Eq. 4).26) Our present research is focused on how the substituent on the double bond changes the stereoselectivities of the aziridine formation. We expected that the introduction of the substituent on the double bond would improve the trans-selectivity in the base-mediated aziridination by increasing the unfavorable steric interaction in the anionic intermediates leading to the cis-aziridines. Detailed here is a highly stereodivergent synthesis of 2,3-cis-2-alkenylaziridines 7 (Eq. 5) and 2,3-trans-isomers 8 (Eq. 6), by the palladium-catalyzed decarboxylative ring closure of carbonates 6a and the base-mediated aziridination of mesylates 6b, respectively, from single allylic alcohols having an alkyl group (R 3 ) on the double bond. a Graduate School of Pharmaceutical Sciences, Osaka University; 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan: and b Graduate School of Pharmaceutical Sciences, Kyoto University; Sakyo-ku, Kyoto 606-8501, Japan. Received September 18, 2003; accepted October 15, 2003; published online...

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Section: Palladium(0)-catalyzed 23-cis-selective Aziridination Reactsupporting

confidence: 75%

mentioning

confidence: 99%

Stereodivergent Synthesis of Chiral 2-Alkenylaziridines: Palladium(0)-Catalyzed 2,3-cis-Selective Aziridination and Base-Mediated 2,3-trans-Selective Aziridination

Ohno

Takemoto

Fujii

et al. 2004

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…Because of its broad specificity towards a wide range of aromatic hydrocarbons, NDO can produce chiral petrochemical-based precursors for the synthesis of specialty chemicals (70,216,509,510). Chiral cyclohexadiene diols are potential precursors for the enantiospecific synthesis of many bioactive molecules, and toluene dioxygenase has been used for biosynthesis of enantiomers of erythrose (78,99,266,555,665). cis-Chlorodihydrodiol is an extremely versatile synthon (265).…”

Section: Enzymatic Upgrading Of Petroleum Fractions and Pure Hydrocarmentioning

confidence: 99%

Recent Advances in Petroleum Microbiology

Hamme¹,

Singh

Ward

2003

Microbiol Mol Biol Rev

1,201

640

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Recent advances in molecular biology have extended our understanding of the metabolic processes related to microbial transformation of petroleum hydrocarbons. The physiological responses of microorganisms to the presence of hydrocarbons, including cell surface alterations and adaptive mechanisms for uptake and efflux of these substrates, have been characterized. New molecular techniques have enhanced our ability to investigate the dynamics of microbial communities in petroleum-impacted ecosystems. By establishing conditions which maximize rates and extents of microbial growth, hydrocarbon access, and transformation, highly accelerated and bioreactor-based petroleum waste degradation processes have been implemented. Biofilters capable of removing and biodegrading volatile petroleum contaminants in air streams with short substrate-microbe contact times (<60 s) are being used effectively. Microbes are being injected into partially spent petroleum reservoirs to enhance oil recovery. However, these microbial processes have not exhibited consistent and effective performance, primarily because of our inability to control conditions in the subsurface environment. Microbes may be exploited to break stable oilfield emulsions to produce pipeline quality oil. There is interest in replacing physical oil desulfurization processes with biodesulfurization methods through promotion of selective sulfur removal without degradation of associated carbon moieties. However, since microbes require an environment containing some water, a two-phase oil-water system must be established to optimize contact between the microbes and the hydrocarbon, and such an emulsion is not easily created with viscous crude oil. This challenge may be circumvented by application of the technology to more refined gasoline and diesel substrates, where aqueous-hydrocarbon emulsions are more easily generated. Molecular approaches are being used to broaden the substrate specificity and increase the rates and extents of desulfurization. Bacterial processes are being commercialized for removal of H2S and sulfoxides from petrochemical waste streams. Microbes also have potential for use in removal of nitrogen from crude oil leading to reduced nitric oxide emissions provided that technical problems similar to those experienced in biodesulfurization can be solved. Enzymes are being exploited to produce added-value products from petroleum substrates, and bacterial biosensors are being used to analyze petroleum-contaminated environments

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“…The C-ring 18, the precursor of the key α-alkoxy bridgehead radical species, possessed the complex cyclohexane structure decorated with the five contiguous stereocenters (C8, 9,11,13,14), along with the bridgehead O,Se-acetal and the caged orthoester structures. Toward the synthesis of C-ring 18, we selected lactol 19 72,73) as the starting material from which a series of stereoselective transformations and optimization of the order of functionalization would be implemented.…”

Section: %mentioning

confidence: 99%

Radical-Mediated Three-Component Reaction: A Study toward the Total Synthesis of Resiniferatoxin

Urabe

2015

CHEMICAL & PHARMACEUTICAL BULLETIN

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This review summarizes the efforts to develop a radical-mediated three-component reaction and its application to a convergent approach to synthesize the 5/7/6-tricyclic framework (ABC-rings) of the densely functionalized dephnane diterpene, resiniferatoxin. The α-alkoxy bridgehead radical species, which was designed as the radical donor of the three-component reaction, was generated from O,Se-and O,Te-acetals under two different conditions. The generated α-alkoxy bridgehead radical effectively underwent the threecomponent reaction with α,β-unsaturated ketones and allyltributyltin/aldehyde under each of the conditions, giving rise to a wide variety of multiply functionalized 2,3-trans disubstituted cyclopentenone moieties. One of the established reactions was utilized as the key assembling reaction of the ABC-tricyclic framework of resiniferatoxin. The reaction of the bridgehead radical of the highly functionalized 6-membered C-ring, the 5-membered A-ring, and an allyltributyltin derivative effectively produced the C4-branched AC-rings. The last B-ring was constructed from the coupling adduct in two steps through the 7-endo cyclization, delivering the tricyclic framework possessing the correct C8 and 9-stereocenters of resiniferatoxin. The present methods demonstrate the power of the three-component reaction using an α-alkoxy bridgehead radical in a convergent approach to the complex architectures of daphnane diterpenes.

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Microbial oxidation of chloroaromatics in the enantiodivergent synthesis of pyrrolizidine alkaloids: trihydroxyheliotridanes

Cited by 170 publications

References 0 publications

Stereodivergent Synthesis of Chiral 2-Alkenylaziridines: Palladium(0)-Catalyzed 2,3-cis-Selective Aziridination and Base-Mediated 2,3-trans-Selective Aziridination

Stereodivergent Synthesis of Chiral 2-Alkenylaziridines: Palladium(0)-Catalyzed 2,3-cis-Selective Aziridination and Base-Mediated 2,3-trans-Selective Aziridination

Recent Advances in Petroleum Microbiology

Radical-Mediated Three-Component Reaction: A Study toward the Total Synthesis of Resiniferatoxin

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