- Bicyclic enol cyclocarbamates inhibit penicillin-binding proteins
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Natural products form attractive leads for the development of chemical probes and drugs. The antibacterial lipopeptide Brabantamide A contains an unusual enol cyclocarbamate and we used this scaffold as inspiration for the synthesis of a panel of enol cyclocarbamate containing compounds. By equipping the scaffold with different groups, we identified structural features that are essential for antibacterial activity. Some of the derivatives block incorporation of hydroxycoumarin carboxylic acid-amino d-alanine into the newly synthesized peptidoglycan. Activity-based protein-profiling experiments revealed that the enol carbamates inhibit a specific subset of penicillin-binding proteins in B. subtilis and S. pneumoniae.
- Dockerty, Paul,Edens, Jerre G.,Tol, Menno B.,Morales Angeles, Danae,Domenech, Arnau,Liu, Yun,Hirsch, Anna K. H.,Veening, Jan-Willem,Scheffers, Dirk-Jan,Witte, Martin D.
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- IMPROVED METHOD FOR THE PREPARATION OF ENANTIOMERICALLY ENRICHED SECONDARY ALCOHOLS BY THE ADDITION OF ORGANOALUMINIUM REAGENTS TO CARBONYL COMPOUNDS
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A process for converting a carbonyl group within a substrate to a chiral alcohol moiety comprising reacting the carbonyl containing substrate with an organoaluminium reagent in the presence of a Group 5-12 transition metal based catalyst which is complexed with a chiral ligand; novel chiral ligands and organoluminium reagents, a chiral ligand or organoaluminium reagent for use in the process.
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Page/Page column 25
(2008/06/13)
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- Remarkably stable (Me3Al)2·DABCO and stereoselective nickel-catalyzed AlR3 (R = Me, Et) additions to aldehydes
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(Chemical Equation Presented) Weigh it out in air! The DABAL reagent (Me3Al)2·(DABCO) (DABCO = 1,4-diazabicyclo[2.2.2] octane) can be easily handled under normal laboratory conditions. Furthermore, chiral secondary alcohols can be efficiently prepared from prochiral aldehydes (see scheme; TOF = turnover frequency) by using either DABAL or AIR3 reagents (R = Me, Et). Thus, DABAL can be used as an efficient, convenient alternative to the Schumann-Blum reagent.
- Biswas, Kallolmay,Prieto, Oscar,Goldsmith, Paul J.,Woodward, Simon
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p. 2232 - 2234
(2007/10/03)
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- Interactions of 1,4-diazabicyclo[2.2.2]octane with group III metal trimethyls: Structures of Me3M·N(C2H4) 3N·MMe3 (M = Al, Ga)
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The reactions of (Me3Al)2 and Me3Ga·OEt2 with 1,4-diazabicyclo[2.2.2]octane (dabco) gave the Lewis acid-base complexes Me3M·N(C2H4) 3N·MMe3 (M = Al (1), Ga (2)). These complexes are discrete 2:1 adducts of the metal trialkyl to dabco. 1H NMR spectra revealed an upfield shift of both the dabco methylene protons and the metal alkyl protons on coordination of the Lewis base. Methyl proton resonances move downfield as the metal center is varied from Al to Ga to In (comparisons being made with the previously reported complex trimethylindium 1,4-diazabicyclo[2.2.2]octane).1 Complexes 1 and 2 were also characterized by IR spectroscopy, where it was found that the vibrational frequency for the M-C asymmetric stretching mode is lower for the adduct species than for the parent metal trimethyls. The molecular structures of 1 and 2, which are isostructural, were determined by X-ray crystallographic analysis. Crystal data for 1: trigonal, R3m, a = b = 11.223 (2) A?, c = 22.757 (8) A?, α = β = 90°, γ = 120°, Z = 6, R = 0.073. Crystal data for 2: trigonal, R3m, a = b = 11.231 (4) A?, c = 22.693 (13) A?, α = β = 90°, γ = 120°, Z = 6, R = 0.043. The molecules have 3m symmetry, and although the Al-C and Ga-C bond lengths were almost equal, the Al-N bond at 2.066 (8) A? was significantly shorter than the Ga-N bond at 2.159 (9) A?. Notable differences in volatility, solubility, and reactivity between 1 and 2 are discussed.
- Bradford, Arleen M.,Bradley, Donald C.,Hursthouse, Michael B.,Motevalli, Majid
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p. 111 - 115
(2008/10/08)
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