The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Marvin J Miller - One of the best experts on this subject based on the ideXlab platform.
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catalytic asymmetric synthesis of the Carbacephem framework
Journal of Organic Chemistry, 1994Co-Authors: Peter R Guzzo, Marvin J MillerAbstract:A catalytic, asymmetric synthesis of the Carbacephem β-lactam framework is reported. The initial asymmetric center was established by catalytic hydrogenation of β-keto ester 12 with (S)-Ru-BINAP. The β-lactam ring was prepared using the hydroxamate approach (14→15). The nitrogen substituent at C7 was introduced by the nucleophile transfer reaction (15→17), and the six-membered ring of the Carbacephem was prepared by a directed Dieckmann condensation (24→25)
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a combined electrophilic diazo and nucleophilic azide transfer reaction for the efficient conversion of an n hydroxy β lactam to a Carbacephem precursor
Bioorganic & Medicinal Chemistry Letters, 1993Co-Authors: Min Teng, Catherine M Gasparski, Matthew A Williams, Marvin J MillerAbstract:Abstract A new method for the synthesis of Carbacephems has been developed. A combined diazo transfer, N-O reduction and azide transfer reaction of N -hydroxy-β-lactam 10b produced 11 in 78.8% yield by treatment with trisyl azide and TMSN 3 in the presence of N,N -diisopropylethylamine. Rhodium-mediated cyclization of diazo/azide 11 to Carbacephem 12 proceeded without interference from the azide.
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Diastereoselective synthesis of the Carbacephem framework
Journal of Organic Chemistry, 1993Co-Authors: B. T. Lotz, Marvin J MillerAbstract:A short, versatile, and diastereoselective method of preparing Carbacephems has been developed. The procedure involves as a key step the aldol condensation of a protected glycine compound with a suitably designed aldehyde. In this step, most of the carbon skeleton of the Carbacephem is assembled, and the two stereocenters of the final bicyclic β-lactam are set. This step also provides well-placed and synthetically useful functionality for further elaboration into the desired target
Perry Clark Heath - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Carbacephem antibiotics synthesis via dieckmann reaction using phenyl esters to direct the regioselectivity of the cyclization
Tetrahedron Letters, 1990Co-Authors: Bill G Jackson, John P Gardner, Perry Clark HeathAbstract:Abstract β-Ketoesters useful for elaboration to Carbacephems were synthesized from a variety of enantiomerically pure diesters. Use of phenyl esters to direct the regioselectivity was demonstrated.
John P Gardner - One of the best experts on this subject based on the ideXlab platform.
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enantioselective synthesis of the Carbacephem antibiotic loracarbef via mitsunobu and dieckmann cyclization from an unnatural amino acid
Tetrahedron Letters, 2003Co-Authors: Jerry W Misner, Jack W. Fisher, John P Gardner, Steve W Pedersen, Kristina L Trinkle, Billy Grinnell Jackson, Tony Y ZhangAbstract:The nucleus of the Carbacephem antibiotic loracarbef was synthesized in a highly efficient and enantioselective fashion from 2S,3S-2-amino-3-hydroxy-6-heptenoic acid (AHHA), which was derived from enzyme-catalyzed condensation of glycine and 4-pentenaldehyde. The bicyclic framework of this compound was established through sequential Mitsunobu reaction and aldol condensations.
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synthesis of Carbacephem antibiotics synthesis via dieckmann reaction using phenyl esters to direct the regioselectivity of the cyclization
Tetrahedron Letters, 1990Co-Authors: Bill G Jackson, John P Gardner, Perry Clark HeathAbstract:Abstract β-Ketoesters useful for elaboration to Carbacephems were synthesized from a variety of enantiomerically pure diesters. Use of phenyl esters to direct the regioselectivity was demonstrated.
Bill G Jackson - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Carbacephem antibiotics synthesis via dieckmann reaction using phenyl esters to direct the regioselectivity of the cyclization
Tetrahedron Letters, 1990Co-Authors: Bill G Jackson, John P Gardner, Perry Clark HeathAbstract:Abstract β-Ketoesters useful for elaboration to Carbacephems were synthesized from a variety of enantiomerically pure diesters. Use of phenyl esters to direct the regioselectivity was demonstrated.
K. Wettich - One of the best experts on this subject based on the ideXlab platform.
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Comparison of loracarbef (LY163892) versus amoxicillin in the treatment of bronchopneumonia and lobar pneumonia
Infection, 1992Co-Authors: O. Müller, K. WettichAbstract:Loracarbef, der erste Vertreter der neuen Substanzklasse der Carbacephem-Antibiotika, wurde in einer randomisierten doppelblinden Parallelgruppen-Studie bei 84 erwachsenen Patienten mit ambulant erworbener Broncho- bzw. Lobärpneumonie im Vergleich mit Amoxicillin auf seine Wirksamkeit und Sicherheit geprüft. Bei zweimal täglicher Gabe hatte Loracarbef dieselbe klinische und bakteriologische Wirksamkeit wie die dreimal tägliche Verabreichung von Amoxicillin. Die Nebenwirkungen waren in beiden Gruppen meist leichtgradig und passager. Die gute Wirksamkeit gegenüber den wichtigsten Erregern der ambulant erworbenen bakteriellen Pneumonie und die bessere Betalactamasestabilität sowie die längere Halbwertszeit im Vergleich zu Amoxicillin und die nur zweimal tägliche Verabreichung sind Vorteile von Loracarbef hinsichtlich der therapeutischen Sicherheit und der Patientenfreundlichkeit. Loracarbef (LY163892), a Carbacephem, is the first of a new class of β-lactam compounds. A 14-day, double-blind, randomized, parallel treatment study compared loracarbef (400 mg b.i.d.; n=169) and amoxicillin (500 mg t.i.d.; n=167) in the treatment of lobar pneumonia and bronchopneumonia. Forty-four patients in the loracarbef group and 40 patients in the amoxicillin group were evaluable for efficacy analysis. Streptococcus pneumoniae and Haemophilus influenzae were isolated from pure or mixed cultures in 45.5% of the evaluable patients, with S. pneumoniae being isolated most frequently. Favourable clinical responses (cure or improvement) in the loracarbef-treated group (42/44; 95.5%) were similar to those in the amoxicillin-treated group (38/40; 95%). A favourable bacteriological response was observed for 36/44 (81.8%) loracarbef-treated patients compared with 28/40 (70%) amoxicillin-treated patients (p=0.2). Adverse events were similar in both groups. Withdrawal of treatment was required in three patients in each group due to gastrointestinal events or rash/allergic exanthema. These data support the conclusion that loracarbef and amoxicillin have comparable efficacy and safety in the treatment of bronchopneumonia and lobar pneumonia caused by susceptible pathogens. However, loracarbef can be administered twice daily, offering the advantage of improved patient compliance. It is also active against β-lactamse producing organisms.
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Comparison of loracarbef (LY163892) versus amoxicillin in the treatment of bronchopneumonia and lobar pneumonia.
Infection, 1992Co-Authors: O. Müller, K. WettichAbstract:Loracarbef (LY163892), a Carbacephem, is the first of a new class of β-lactam compounds. A 14-day, double-blind, randomized, parallel treatment study compared loracarbef (400 mg b.i.d.; n=169) and amoxicillin (500 mg t.i.d.; n=167) in the treatment of lobar pneumonia and bronchopneumonia. Forty-four patients in the loracarbef group and 40 patients in the amoxicillin group were evaluable for efficacy analysis.Streptococcus pneumoniae andHaemophilus influenzae were isolated from pure or mixed cultures in 45.5% of the evaluable patients, withS. pneumoniae being isolated most frequently. Favourable clinical responses (cure or improvement) in the loracarbef-treated group (42/44; 95.5%) were similar to those in the amoxicillin-treated group (38/40; 95%). A favourable bacteriological response was observed for 36/44 (81.8%) loracarbef-treated patients compared with 28/40 (70%) amoxicillin-treated patients (p=0.2). Adverse events were similar in both groups. Withdrawal of treatment was required in three patients in each group due to gastrointestinal events or rash/allergic exanthema. These data support the conclusion that loracarbef and amoxicillin have comparable efficacy and safety in the treatment of bronchopneumonia and lobar pneumonia caused by susceptible pathogens. However, loracarbef can be administered twice daily, offering the advantage of improved patient compliance. It is also active against β-lactamse producing organisms.