Stereoselective Modification of <i>N</i>-(α-Hydroxyacyl)-glycinesters via Palladium-Catalyzed Allylic Alkylation

Horn, Alexander; Kazmaier, Uli

doi:10.1021/acs.orglett.9b01497

Cited by 14 publications

(7 citation statements)

References 80 publications

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“…The isolated products were characterized by multinuclear NMR and HRMS analysis. The spectral data were in good agreement with the previously reported data. − The characterization of the isolated products is detailed in the Supporting Information.…”

Section: Methodssupporting

confidence: 87%

PNCNP Pincer Platinum Chloride Complex as a Catalyst for the Hydrosilylation of Unsaturated Carbon-Heteroatom Bonds

et al. 2022

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A PNCNP pincer-ligated platinum(II) chloride complex [2,6-( t Bu 2 PNH) 2 C 6 H 3 ]PtCl (1a) was synthesized and fully characterized. Complex 1a was applied to the catalytic hydrosilylation of unsaturated carbon-heteroatom bonds. For comparison, the corresponding hydride complex [2,6-( t Bu 2 PNH) 2 C 6 H 3 ]PtH (1b) and the related POCOP pincer chloride complex [2,6-( t Bu 2 PO) 2 C 6 H 3 ]PtCl (1c) were also used to catalyze the reactions. It was found that 1a is a good catalyst for the hydrosilylation of both C�O and C�N bonds. Wide ranges of aldimines, ketimines, aldehydes, and ketones were hydrosilylated, and the expected amine or alcohol products were obtained in good to excellent yields. The reactions also feature good functional group compatibility. Complex 1a represents the most effective transition metal catalyst for the hydrosilylation of the C�N bond and is among the best transition metal catalysts for the hydrosilylation of the C�O bond. The reactions are likely catalyzed by a cationic platinum(II) species generated from complex 1a during the reactions.

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Section: Methodssupporting

confidence: 87%

PNCNP Pincer Platinum Chloride Complex as a Catalyst for the Hydrosilylation of Unsaturated Carbon-Heteroatom Bonds

et al. 2022

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“…(E)-4-phenylbut-3-en-2-yl acetate (2a): Yield 96% (2.7 g), spectroscopic data consistent with those reported in the literature [67].…”

Section: -General Proceduressupporting

confidence: 83%

Free and Immobilized Lecitase™ Ultra as the Biocatalyst in the Kinetic Resolution of (E)-4-Arylbut-3-en-2-yl Esters

et al. 2020

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The influence of buffer type, co-solvent type, and acyl chain length was investigated for the enantioselective hydrolysis of racemic 4-arylbut-3-en-2-yl esters using Lecitase™ Ultra (LU). Immobilized preparations of the Lecitase™ Ultra enzyme had significantly higher activity and enantioselectivity than the free enzyme, particularly for 4-phenylbut-3-en-2-yl butyrate as the substrate. Moreover, the kinetic resolution with the immobilized enzyme was achieved in a much shorter time (24–48 h). Lecitase™ Ultra, immobilized on cyanogen bromide-activated agarose, was particularly effective, producing, after 24 h of reaction time in phosphate buffer (pH 7.2) with acetone as co-solvent, both (R)-alcohols and unreacted (S)-esters with good to excellent enantiomeric excesses (ee 90–99%). These conditions and enzyme were also suitable for the kinetic separation of racemic (E)-4-phenylbut-3-en-2-yl butyrate analogs containing methyl substituents on the benzene ring (4b,4c), but they did not show any enantioselectivity toward (E)-4-(4’-methoxyphenyl)but-3-en-2-yl butyrate (4d).

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“…Compound 23b with an ( R )-configuration was eluted at 12.54 min, whereas compound 23c with ( S )-configuration was eluted at 9.88 min with ee values >99% (Supporting Information Figure S1). ( Z )-selective reduction of the alkyne ( 22a ) to cis-isomer ( 25 ) was accomplished by the treatment of the Lindlar catalyst and 1,4-benzoquinone under an atmosphere of hydrogen, followed by desilylation with TBAF . The alkynyl alcohol 27 was obtained from 22a in 94% yield via catalytic hydrogenation and subsequent desilylation.…”

Section: Resultsmentioning

confidence: 99%

“…(Z)-selective reduction of the alkyne (22a) to cisisomer (25) was accomplished by the treatment of the Lindlar catalyst and 1,4-benzoquinone under an atmosphere of hydrogen, followed by desilylation with TBAF. 32 The alkynyl alcohol 27 was obtained from 22a in 94% yield via catalytic hydrogenation and subsequent desilylation.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Discovery and Characterization of Pure RhlR Antagonists against Pseudomonas aeruginosa Infections

et al. 2020

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Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic human pathogen that forms biofilms and produces virulence factors via quorum sensing (QS). Blocking the QS system in P. aeruginosa is an excellent strategy to reduce biofilm formation and the production of virulence factors. RhlR plays an essential role in the QS system of P. aeruginosa. We synthesized 55 analogues based on the chemical structure of 4-gingerol and evaluated their RhlR inhibitory activities using the cell-based reporter strain assay. Comprehensive structure–activity relationship studies identified the alkynyl ketone 30 as the most potent RhlR antagonist. This compound displayed selective RhlR antagonism over LasR and PqsR, strong inhibition of biofilm formation, and reduced production of virulence factors in P. aeruginosa. Furthermore, the survival rate of Tenebrio molitor larvae treated with 30 in vivo greatly improved. Therefore, compound 30, a pure RhlR antagonist, can be utilized for developing QS-modulating molecules in the control of P. aeruginosa infections.

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Stereoselective Modification of N-(α-Hydroxyacyl)-glycinesters via Palladium-Catalyzed Allylic Alkylation

Cited by 14 publications

References 80 publications

PNCNP Pincer Platinum Chloride Complex as a Catalyst for the Hydrosilylation of Unsaturated Carbon-Heteroatom Bonds

PNCNP Pincer Platinum Chloride Complex as a Catalyst for the Hydrosilylation of Unsaturated Carbon-Heteroatom Bonds

Free and Immobilized Lecitase™ Ultra as the Biocatalyst in the Kinetic Resolution of (E)-4-Arylbut-3-en-2-yl Esters

Discovery and Characterization of Pure RhlR Antagonists against Pseudomonas aeruginosa Infections

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