scholarly journals Ring-Opening Fluorination of Bicyclic Azaarenes

2022 ◽  
Author(s):  
Masaaki Komatsuda ◽  
Ayane Suto ◽  
Hiroki Kondo Jr. ◽  
Hiroyuki Takada ◽  
Kenta Kato ◽  
...  
Keyword(s):  

We have discovered a ring-opening fluorination of bicyclic azaarenes. Upon treatment of bicyclic azaarenes such as pyrazolopyridines with electrophilic fluorinating agents, fluorination of the aromatic ring is followed by a...

2009 ◽  
Vol 143 (1-2) ◽  
pp. 115-119 ◽  
Author(s):  
Pedro Castaño ◽  
Alazne Gutiérrez ◽  
Inés Villanueva ◽  
Barbara Pawelec ◽  
Javier Bilbao ◽  
...  

ChemInform ◽  
2010 ◽  
Vol 29 (28) ◽  
pp. no-no
Author(s):  
B. HILL ◽  
M. DE VLEESCHAUWER ◽  
K. HOUDE ◽  
M. BELLEY

ChemInform ◽  
2005 ◽  
Vol 36 (28) ◽  
Author(s):  
Michel Belley ◽  
Zohra Douida ◽  
John Mancuso ◽  
Marc De Vleeschauwer
Keyword(s):  

2021 ◽  
Vol 87 (8) ◽  
Author(s):  
Jose M. Perez ◽  
Wayne S. Kontur ◽  
Carson Gehl ◽  
Derek M. Gille ◽  
Yanjun Ma ◽  
...  

ABSTRACT Lignin is a plant heteropolymer composed of phenolic subunits. Because of its heterogeneity and recalcitrance, the development of efficient methods for its valorization still remains an open challenge. One approach to utilize lignin is its chemical deconstruction into mixtures of monomeric phenolic compounds, followed by biological funneling into a single product. Novosphingobium aromaticivorans DSM 12444 has been previously engineered to produce 2-pyrone-4,6-dicarboxylic acid (PDC) from depolymerized lignin by simultaneously metabolizing multiple aromatics through convergent routes involving the intermediates 3-methoxygallic acid (3-MGA) and protocatechuic acid (PCA). We investigated enzymes predicted to be responsible for O-demethylation and oxidative aromatic ring opening, two critical reactions involved in the metabolism of phenolic compounds by N. aromaticivorans. The results showed the involvement of DesA in O-demethylation of syringic and vanillic acids, LigM in O-demethylation of vanillic acid and 3-MGA, and a new O-demethylase, DmtS, in the conversion of 3-MGA into gallic acid (GA). In addition, we found that LigAB was the main aromatic ring-opening dioxygenase involved in 3-MGA, PCA, and GA metabolism and that a previously uncharacterized dioxygenase, LigAB2, had high activity with GA. Our results indicate a metabolic route not previously identified in N. aromaticivorans that involves O-demethylation of 3-MGA to GA. We predict that this pathway channels ∼15% of the carbon flow from syringic acid, with the rest following ring opening of 3-MGA. The new knowledge obtained in this study allowed for the creation of an improved engineered strain for the funneling of aromatic compounds that exhibits stoichiometric conversion of syringic acid into PDC. IMPORTANCE For lignocellulosic biorefineries to effectively contribute to reduction of fossil fuel use, they need to become efficient at producing chemicals from all major components of plant biomass. Making products from lignin will require engineering microorganisms to funnel multiple phenolic compounds to the chemicals of interest, and N. aromaticivorans is a promising chassis for this technology. The ability of N. aromaticivorans to efficiently and simultaneously degrade many phenolic compounds may be linked to having functionally redundant aromatic degradation pathways and enzymes with broad substrate specificity. A detailed knowledge of aromatic degradation pathways is thus essential to identify genetic engineering targets to maximize product yields. Furthermore, knowledge of enzyme substrate specificity is critical to redirect flow of carbon to desired pathways. This study described an uncharacterized pathway in N. aromaticivorans and the enzymes that participate in this pathway, allowing the engineering of an improved strain for production of PDC from lignin.


2013 ◽  
Vol 10 (3) ◽  
pp. 245 ◽  
Author(s):  
Harshal M. Parikh ◽  
Harvey E. Jeffries ◽  
Ken G. Sexton ◽  
Deborah J. Luecken ◽  
Richard M. Kamens ◽  
...  

Environmental context Regulatory air quality models used to develop strategies to reduce ozone and other pollutants must be able to accurately predict ozone produced from aromatic hydrocarbons. In urban areas, major sources of aromatic hydrocarbons are gasoline and diesel-powered vehicles. Our findings show that the representation of aromatic hydrocarbon chemistry in air quality models is an area of high uncertainty Abstract Simulations using seven chemical mechanisms are intercompared against O3, NOx and hydrocarbon data from photooxidation experiments conducted at the University of North Carolina outdoor smog chamber. The mechanisms include CB4–2002, CB05, CB05-TU, a CB05 variant with semi-explicit aromatic chemistry (CB05RMK), SAPRC07, CS07 and MCMv3.1. The experiments include aromatics, unsaturated dicarbonyls and volatile organic compound (VOC) mixtures representing a wide range of urban environments with relevant hydrocarbon species. In chamber simulations the sunlight is characterised using new solar radiation modelling software. A new heterogeneous chamber wall mechanism is also presented with revised chamber wall chemical processes. Simulations from all mechanisms, except MCMv3.1, show median peak O3 concentration relative errors of less than 25% for both aromatic and VOC mixture experiments. Although MCMv3.1 largely overpredicts peak O3 levels, it performs relatively better in predicting the peak NO2 concentration. For aromatic experiments, all mechanisms except CB4–2002, largely underpredict the NO–NO2 crossover time and over-predict both the absolute NO degradation slope and the slope of NO2 concentration rise. This suggests a major problem of a faster and earlier NO to NO2 oxidation rate across all the newer mechanisms. Results from individual aromatic and unsaturated dicarbonyl experiments illustrate the unique photooxidation chemistry and O3 production of several aromatic ring-opening products. The representation of these products as a single mechanism species in CB4–2002, CB05 and CB05-TU is not adequate to capture the O3 temporal profile. In summary, future updates to chemical mechanisms should focus on the chemistry of aromatic ring-opening products.


Structure ◽  
1999 ◽  
Vol 7 (8) ◽  
pp. 953-965 ◽  
Author(s):  
Keisuke Sugimoto ◽  
Toshiya Senda ◽  
Hisae Aoshima ◽  
Eiji Masai ◽  
Masao Fukuda ◽  
...  

2021 ◽  
Author(s):  
Masayuki Komatsuda ◽  
Ayane Suto ◽  
Hiroki Kondo Jr. ◽  
Hiroyuki Takada ◽  
Kenta Kato ◽  
...  

We have discovered a ring-opening fluorination of bicyclic azaarenes. Upon treatment of bicyclic azaarenes such as pyrazolopyridines with electrophilic fluorinating agents, fluorination of the aromatic ring is followed by a ring-opening reaction. Although this overall trans-formation can be classified as an electrophilic fluorination of an aromatic ring, it is a novel type of fluorination that results in construction of tertiary carbon–fluorine bonds. The present protocol can be applied to a range of bicyclic azaarenes, tolerating azines and a variety of functional groups. Additionally, mechanistic studies and enantioselective fluorination have been examined.


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