- METHOD OF PREPARING INTERMEDIATES OF PENEM ANTIBIOTICS
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The present invention relates to a method of preparing bicyclic keto esters, which are intermediates for carbapenem-based antibiotics. The method of preparing carbapenem-based antibiotic intermediates according to the present invention has not only the fast reaction rate using co-catalysts and specific reaction solvents which may be allowed to have high activity of rhodium catalysts, but also reduces the amount of expensive rhodium catalysts. Therefore, the present invention is very economical and useful, in industrial aspects.
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Page/Page column 28; 30
(2009/06/27)
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- Simple and Condensed β-Lactams. Part 9. Elaboration of the 3-(1-Hydroxyethyl) Side Chains of Potential Intermediates of Carbapenem Antibiotics via the 2-Methyl-1,3-dioxolan-2-yl Group
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Deketalization of the trans compounds methyl and ethyl (2RS,3RS)-1-(2,4-dimethoxybenzyl)-3-(2-methyl-1,3-dioxolan-2-yl)-4-oxoazetidine-2-carboxylates 5b and 5c, and of the cis isomer (6b) of the latter leads to 85:15 mixtures of the trans- and cis-compounds methyl (2RS,3RS)- and (2RS,3SR)-3-acetyl-1-(2,4-dimethoxybenzyl)-4-oxoazetidine-2-carboxylate (7a) and (8a), respectively of the corresponding ethyl esters (7b) and (8b).Sodium borohydride reduction of the mixture of the trans- and cis-esters (7b) and (8b) gives a mixture of the 1'-epimeric trans-compounds ethyl(2RS,3RS)-1-(2,4-dimethoxybenzyl)-3--4-oxazetidine-2-carboxylate (9b) and (10b).Similar mixtures of 1'-epimeric compounds of the types (9) and (10), carrying a variety of substituents attached to position 2 of their azetidine rings were obtained by successive deketalization and reduction of the corresponding trans-(5) and cis-(6) compounds or their mixtures, as well as by other methods.Ring closure of a mixture of the pair of the 1'-epimeric trans-compounds p-nitrobenzyl 2-diazo-4--4-oxo-azetidin-2-yl>-3-oxobutanoates (9n) and (10n) gave a mixture of the 1'-epimeric compounds p-nitrobenzyl 6--2,7-dioxo-(3RS,5RS,6SR)-carbapenam-3-carboxylates (11) and (12) which was converted into a mixture (13) of the 1'-epimeric bis-protected thienamycin analogues p-nitrobenzyl 2-(2-formylaminoethylthio)-6--7-oxo-(5RS,6SR)-carbapen-2-em-3-carboxylates.
- Fetter, Jozsef,Lempert, Karoly,Kajtar-Peredy, Maria,Simig, Gyula
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p. 1135 - 1142
(2007/10/02)
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- A PRACTICAL SYNTHESIS OF (+/-)-THIENAMYCIN
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An efficient and operationally simply synthesis of (+/-)-thienamycin is described.
- Melillo, D.G.,Shinkai, I.,Liu, T.,Ryan, K.,Sletzinger, M.
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p. 2783 - 2786
(2007/10/02)
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