Acetophenone

Selective Synthesis of 3-(9 H-Carbazol-2-yl)indolin-2-ones and Spiro[tetrahydrocarbazole-3,3'-oxindoles] via a HOTf Catalyzed Three-Component Reaction.[Pubmed:29696973]

J Org Chem. 2018 Jun 1;83(11):5909-5919.

A HOTf catalyzed three-component reaction of indoles, Acetophenones, and ( E)-3-phenacylideneoxindolinones resulted in the unexpected polysubstituted 3-(9 H-carbazol-2-yl)indolin-2-ones in good yields. A similar reaction with various cyclic ketones afforded the corresponding carbocyclic fused 3-(9 H-carbazol-2-yl)indolin-2-ones. On the other hand, ( E)-3-arylideneoxindolinones in the three-component reaction gave the expected spiro[tetrahydrocarbazole-3,3'-oxindoles] through a domino alkenylation/Diels-Alder reaction. The unusual different reactivity of ( E)-3-phenacylideneoxindolinones and ( E)-3-arylideneoxindolinones in the three-component reactions was believed to involve the different reaction paths caused by the existence of the carbonyl group.

Identification of toxic substances in phenol-acetone wastewater on activated sludge and selective toxicity removal performance with ferrous pretreatment.[Pubmed:29736641]

Environ Sci Pollut Res Int. 2018 Jul;25(20):19628-19634.

We investigated the effects of toxic wastewater generated during the production of phenol-acetone on activated sludge and tested pretreatment methods to selectively remove the toxicity. We found that the microbial activity in the activated sludge was inhibited by the wastewater, in which cumene hydroperoxide (CHP) with a medium effective concentration (EC50) of 225 mg L(-1) was the main toxic substance. We tested one pretreatment method with ferrous iron to selectively remove the CHP. The CHP decomposition process, which mainly produced Acetophenone, was very quick. The CHP was selectively transformed into low-toxicity organics, and a maximum of 92% was removed when 1.08 mmol L(-1) of ferrous iron was added, for a reaction time of 10 min, a pH of 5, and a temperature of 25 degrees C, and the resulting wastewater only slightly inhibited the oxygen uptake rate of activated sludge. The acclimation of activated sludge was accelerated, and a COD removal rate of more than 85% was achieved within a week. Our results confirm that ferrous iron provides a cost-effective method to selectively remove toxins from wastewater.

A new anthraquinoid ligand for the iron-catalyzed hydrosilylation of carbonyl compounds at room temperature: new insights and kinetics.[Pubmed:29766169]

Dalton Trans. 2018 May 29;47(21):7272-7281.

The reaction of 1-((2-(pyridin-2-yl)ethyl)amino)anthraquinone with either Fe(HMDS)2 or Li(HMDS)/FeCl2 allowed the preparation of a new anthraquinoid-based iron(ii) complex active in the hydrosilylations of carbonyls. The new complex Fe(2)2 was characterized by single-crystal X-ray diffraction, infrared spectroscopy, NMR, and high resolution mass spectrometry (electrospray ionization). Superconducting quantum interference device (SQUID) magnetometry established no spin crossover behavior with an S = 2 state at room temperature. This complex was determined to be an effective catalyst for the hydrosilylation of aldehydes and ketones, exhibiting turnover frequencies of up to 63 min-1 with a broad functional group tolerance by just using 0.25 mol% of the catalyst at room temperature, and even under solvent-free conditions. The aldehyde hydrosilylation makes it one of the most efficient first-row transition metal catalysts for this transformation. Kinetic studies have proven first-order dependences with respect to Acetophenone and Ph2SiH2 and a fractional order in the case of the catalyst.

Synthesis of Enantiomerically Enriched Drug Precursors by Lactobacillus paracasei BD87E6 as a Biocatalyst.[Pubmed:29667758]

Chem Biodivers. 2018 Jun;15(6):e1800028.

Global sales of single enantiomeric drug products are growing at an alarming rate every year. A total of 7 bacterial strains were screened for their ability to reduce Acetophenones to its corresponding alcohol. Among these strains Lactobacillus paracasei BD87E6 was found to be the most successful biocatalyst to reduce the ketones to the corresponding alcohols. The reaction conditions were systematically optimized for the reducing agent Lactobacillus paracasei BD87E6, which showed high enantioselectivity and conversion for the bioreduction. The preparative scale asymmetric reduction of 3-methoxyAcetophenone (1h) by Lactobacillus paracasei BD87E6 gave (R)-1-(3-methoxyphenyl)ethanol (2h) with 92% yield and 99% enantiomeric excess. Compound 2h could be used for the synthesis of (S)-rivastigmine which has a great potential for the treatment of Alzheimer's disease. This study demonstrates that Lactobacillus paracasei BD87E6 can be used as a biocatalyst to obtain chiral carbinol with excellent yield and selectivity. The whole cell catalyzed the reductions of ketone substrates on the preparative scale, demonstrating that Lactobacillus paracasei BD87E6 would be a valuable biocatalyst for the preparation of chiral aromatic alcohols of pharmaceutical interest.

Synthesis of fused pyrroles containing 4-hydroxycoumarins by regioselective metal-free multicomponent reactions.[Pubmed:29667668]

Org Biomol Chem. 2018 May 2;16(17):3289-3302.

The reaction of arylglyoxals, 4-hydroxycoumarin, and aromatic amines such as 7-amino-2-methylchromone, 6/7-aminoflavone, 7-amino-4-methylcoumarin, 1-amino-9-fluorenone, 1-aminoanthraquinone and aniline derivatives in acetic acid medium under microwave conditions provides the corresponding regioselective fused pyrroles having hydroxycoumarin and aryl substituents. Alternatively, we have developed another method using in situ arylglyoxals from Acetophenone derivatives by I2/DMSO promoted C-H oxidation followed by one-pot three component cyclization reactions to provide similar fused pyrroles. Using both the methods a series of novel pyrroles fused with pharmacologically important chromone, flavone, coumarin, fluorenone, and anthraquinone moieties were synthesized under metal-free reaction conditions in good to very good yields within a short reaction time. The structures of the synthesized fused pyrroles have been unambiguously confirmed by spectroscopic techniques, mass analysis and single crystal XRD.

Study of the biochemical formation pathway of aroma compound 1-phenylethanol in tea (Camellia sinensis (L.) O. Kuntze) flowers and other plants.[Pubmed:29655745]

Food Chem. 2018 Aug 30;258:352-358.

After tea leaves, tea (Camellia sinensis) flowers are becoming a second tea plant resource because they contain not only functional metabolites similar to those found in tea leaves, but also predominant amounts of functional metabolites that only occur in tea leaves in small amounts. 1-Phenylethanol (1PE) is a predominant aroma compound found in tea flowers. A 1PE synthase in tea flowers was isolated, functionally characterized, and shown to have the highest catalytic efficiency for the conversion of Acetophenone (AP). To determine why 1PE accumulates more in tea flowers than other plants, we compared their 1PE contents and used a stable isotope labeling method to elucidate the 1PE biosynthetic route. Supplementation with [(2)H8]l-phenylalanine and [(2)H5]AP suggested that most plants containing the enzyme/gene catalyzed the conversion of AP to 1PE. Furthermore, the availability of AP derived from l-phenylalanine was responsible for the difference in 1PE accumulation between tea flowers and other plants.

Identification of potent chromone embedded [1,2,3]-triazoles as novel anti-tubercular agents.[Pubmed:29765644]

R Soc Open Sci. 2018 Apr 4;5(4):171750.

A series of 20 novel chromone embedded [1,2,3]-triazoles derivatives were synthesized via an easy and convenient synthetic procedure starting from 2-hydroxy Acetophenone. The in vitro anti-mycobacterial evaluation studies carried out in this work reveal that seven compounds exhibit significant inhibition against Mycobacterium tuberculosis H37Rv strain with MIC in the range of 1.56-12.5 microg ml(-1). Noticeably, compound 6s was the most potent compound in vitro with a MIC value of 1.56 microg ml(-1). Molecular docking and chemoinformatics studies revealed that compound 6s displayed drug-like properties against the enoyl-acyl carrier protein reductase of M. tuberculosis further establishing its potential as a potent inhibitor.

Development of microreactors with surface-immobilized biocatalysts for continuous transamination.[Pubmed:29758351]

N Biotechnol. 2018 Dec 25;47:18-24.

The industrial importance of optically pure compounds has thrown a spotlight on omega-transaminases that have shown a high potential for the synthesis of bioactive compounds with a chiral amine moiety. The implementation of biocatalysts in industrial processes relies strongly on fast and cost effective process development, including selection of a biocatalyst form and the strategy for its immobilization. Here, microscale reactors with selected surface-immobilized amine-transaminase (ATA) in various forms are described as platforms for high-throughput process development. Wild type ATA (ATA-wt) from a crude cell extract, as well as Escherichia coli cells intracellularly overexpressing the enzyme, were immobilized on the surfaces of meander microchannels of disposable plastics by means of reactor surface silanization and glutaraldehyde bonding. In addition, a silicon/glass microchannel reactor was used for immobilization of an ATA-wt, genetically engineered to contain a silica-binding module (SBM) at the N-terminus (N-SBM-ATA-wt), leading to immobilization on the non-modified inner microchannel surface. Microreactors with surface-immobilized biocatalysts were coupled with a quenching system and at-line HPLC analytics and evaluated based on continuous biotransformation, yielding Acetophenone and l-alanine. E. coli cells and N-SBM-ATA-wt were efficiently immobilized and yielded a volumetric productivity of up to 14.42gL(-1)h(-1), while ATA-wt small load resulted in two orders of magnitude lower productivity. The miniaturized reactors further enabled in-operando characterization of biocatalyst stability, crucial for successful transfer to a production scale.