Direct Asymmetric anti‐Mannich‐Type Reactions Catalyzed by a Designed Amino Acid.

Mitsumori, Susumu; Zhang, Haile; Cheong, Paul Ha‐Yeon; Houk, K. N.; Tanaka, Fujie; Barbas, Carlos F.

doi:10.1002/chin.200624031

Cited by 21 publications

(27 citation statements)

References 1 publication

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“…At the same time, precursor VOCs were not fully depleted after 6 h, suggesting that carbonyls should continue to be formed throughout the experiment and not be entirely consumed via a heterogeneous reaction with NH 3 . Given that the postulated heterogeneous reactions (Mannich reaction and/or reaction to form Schiff base) are known to be acid catalyzed (Mitsumori et al, 2006), we suggest that a diffusion limitation to the acidic core of the particle (or to a region where acidity and carbonyls are unavailable) may be responsible for the slow decrease in uptake with time as significant amount of organic material (e.g., in the form of SOA) is added to the seed particles. This would have the effect of reducing the uptake of NH 3 leading to both NOC and NH + 4 , consistent with the derived γ of both.…”

Section: Factors Affecting Reaction Kineticsmentioning

confidence: 97%

Reactive uptake of ammonia to secondary organic aerosols: kinetics of organonitrogen formation

Liu¹,

Liggio²,

Staebler³

et al. 2015

Atmos. Chem. Phys.

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Abstract. As a class of brown carbon, organonitrogen compounds originating from the heterogeneous uptake of NH 3 by secondary organic aerosol (SOA) have received significant attention recently. In the current work, particulate organonitrogen formation during the ozonolysis of α-pinene and the OH oxidation of m-xylene in the presence of ammonia (34-125 ppb) was studied in a smog chamber equipped with a high resolution time-of-flight aerosol mass spectrometer and a quantum cascade laser instrument. A large diversity of nitrogen-containing organic (NOC) fragments was observed which were consistent with the reactions between ammonia and carbonyl-containing SOA. Ammonia uptake coefficients onto SOA which led to organonitrogen compounds were reported for the first time, and were in the range of ∼ 10 −3 -10 −2 , decreasing significantly to < 10 −5 after 6 h of reaction. At the end of experiments (∼ 6 h) the NOC mass contributed 8.9 ± 1.7 and 31.5 ± 4.4 wt % to the total α-pineneand m-xylene-derived SOA, respectively, and 4-15 wt % of the total nitrogen in the system. Uptake coefficients were also found to be positively correlated with particle acidity and negatively correlated with NH 3 concentration, indicating that heterogeneous reactions were responsible for the observed NOC mass, possibly limited by liquid phase diffusion. Under these conditions, the data also indicate that the formation of NOC can compete kinetically with inorganic acid neutralization. The formation of NOC in this study suggests that a significant portion of the ambient particle associated N may be derived from NH 3 heterogeneous reactions with SOA. NOC from such a mechanism may be an important and unaccounted for source of PM associated nitrogen. This mechanism may also contribute to the medium or long-range transport and wet/dry deposition of atmospheric nitrogen.

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Section: Factors Affecting Reaction Kineticsmentioning

confidence: 97%

Reactive uptake of ammonia to secondary organic aerosols: kinetics of organonitrogen formation

Liu¹,

Liggio²,

Staebler³

et al. 2015

Atmos. Chem. Phys.

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“…20,21 The main product has the Schiff base structure ( Figure 1). [22][23][24] The reaction between the amino groups of Col-p and the aldehyde group of DBC is represented by Equation 3:…”

Section: Resultsmentioning

confidence: 99%

Immobilization of collagen peptide on dialdehyde bacterial cellulose nanofibers via covalent bonds for tissue engineering and regeneration

Wen¹,

Zheng²,

Wu³

et al. 2015

IJN

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Bacterial cellulose (BC) is an alternative nanostructured biomaterial to be utilized for a wide range of biomedical applications. Because of its low bioactivity, which restricted its practical application, collagen and collagen hydrolysate were usually composited into BC. It is necessary to develop a new method to generate covalent bonds between collagen and cellulose to improve the immobilization of collagen on BC. This study describes a facile dialdehyde BC/collagen peptide nanocomposite. BC was oxidized into dialdehyde bacterial cellulose (DBC) by regioselective oxidation, and then composited with collagen peptide (Col-p) via covalent bonds to form Schiff’s base type compounds, which was demonstrated by the results of microstructures, contact angle, Col-p content, and peptide-binding ratio. The peptide-binding ratio was further affected by the degree of oxidation, pH value, and zeta potential. In vitro desorption measurement of Col-p suggested a controlled release mechanism of the nanocomposite. Cell tests indicated that the prepared DBC/Col-p composite was bioactive and suitable for cell adhesion and attachment. This work demonstrates that the DBC/Col-p composite is a promising material for tissue engineering and regeneration.

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“…23,24 The reaction is generally supposed to proceed via enamine intermediates. 25 In the past few years, these catalysts have greatly expanded to include 4-substituted-L-proline, [26][27][28][29] N-sulfonylcarboxamides, 30 tetrazole, 31,32 diamine-protonic acid, 33 axially chiral amino acids, 34,35 3-pyrrolidinecarboxylic acid, 36 and prolinamides. [37][38][39][40][41][42][43][44][45] Although the catalyst system has been extended, high enantioselective for a narrow range of substrates and requirement of 30 mol % catalyst loading are usually observed.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric aldol reactions catalyzed by efficient and recyclable silica‐supported proline‐based peptides

Yan

Wang

2008

Chirality

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A series of silica-supported proline-based peptides were synthesized and applied as catalysts for direct asymmetric intermolecular aldol reactions. Among these, a peptide with two L-proline units was found to be the most efficient one for the asymmetric aldol reactions between acetone and aromatic aldehydes. The reactions generated the corresponding products with satisfactory isolated yields (up to 97%) and enantiomeric excesses (up to 96%) in the presence of this catalyst (5 mol %). Furthermore, the silica-supported organocatalyst could be recovered and recycled by a simple filtration of the reaction solution and used for five consecutive trials without loss of its reactivity.

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Direct Asymmetric anti‐Mannich‐Type Reactions Catalyzed by a Designed Amino Acid.

Cited by 21 publications

References 1 publication

Reactive uptake of ammonia to secondary organic aerosols: kinetics of organonitrogen formation

Reactive uptake of ammonia to secondary organic aerosols: kinetics of organonitrogen formation

Immobilization of collagen peptide on dialdehyde bacterial cellulose nanofibers via covalent bonds for tissue engineering and regeneration

Asymmetric aldol reactions catalyzed by efficient and recyclable silica‐supported proline‐based peptides

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