- THE USE OF LIPOPHILIC BETA-LACTAM ANTIBIOTICS AND CARBOXYLATE ESTERS FOR THE TREATMENT OF BACTERIAL INFECTIONS WITHIN CITRUS AND OTHER PLANT SPECIES
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Disclosed is method for converting a beta-lactam antibiotic into a “masked” beta-lactam antibiotic to permit it to cross the waxy cuticle of a plant and then subsequently unmasking the beta-lactam and converting it into an active beta-lactam antibiotic in
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Paragraph 0035-0036; 0038; 0048
(2020/08/05)
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- Studies on the design and synthesis of new monocyclic β-lactams containing substructures of penicillin G
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The studies on design and synthesis of new monocyclic β-lactam esters 4(R/S)-(1′-methoxycarbonylpropyl-2′(R/S)-thio)-3(R)-phenylacetamidoazetidin-2-one (3a) and 4(R/S)-(1′-methoxycarbonyl-2′-methyl-propyl-2′-thio)-3(R)-phenylacetamidoazetidin-2-one (3b) were described. Compounds 3a and 3b were specifically designed to retain all penicillin substructures except the bicyclic system, which would be conceived by cleaving the C(3)-N(4) bond of penicillin G. Compounds 3a and 3b are of particular interest in the context of the structural elucidation of monocyclic β-lactams originated from penicillin. Key intermediates, β-mercapto esters 6a and 6b, were synthesized from conjugate acids 4a and 4b using three-step synthetic sequences, respectively, and 4(S)-acetoxy-3(S)-phenylacetamidoazetidin-2-one (7) was obtained from the degradation of penicillin G. Reactions of 6a and 6b with 7, thus obtained, provided the target compounds 3a and 3b, respectively.
- Lee, Sang Hyup
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p. 2990 - 2994
(2014/12/10)
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- Design and synthesis of new 4-alkylthio monocyclic β-lactams
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New types of monocyclic β-lactams constitute an important class of compounds due to their unique structures and natures. Here, the design and synthesis of new 4-alkylthio monocyclic β-lactams 2a and 3a are reported. Significantly, compounds 2a and 3a, while keeping a monocyclic system, were designed to contain all of the substructures provided by the cleavage of C(2)-C(3) bond in penicillins. Efficient synthetic pathways for compounds 2a and 3a were established based on two different strategies. Compound 2a was synthesized from raw materials, using 4-acetoxyazetidin-2-one as a key intermediate, through a ten-step synthetic sequence in 3% overall yield. Compound 3a was synthesized from potassium salt of penicillin G (17), using the degraded product 20 as a key intermediate, through a six-step synthetic sequence in 11% overall yield. 4-Alkylthioazetidin- 2-one derivatives, introduced in this study, could serve as valuable intermediates for the development of new monocyclic β-lactams.
- Lee, Sang Hyup
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p. 121 - 127
(2013/08/24)
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