Studies on β-lactam antibiotics. I. A novel conversion of penicillins into cephalosporins

Kitamura, Takashi; Teraji, Tsutomu; Saito, Y.; Hashimoto, Masashi; Nakaguchi, Osamu; Oku, Teruo

doi:10.1016/s0040-4039(01)96303-8

Cited by 84 publications

(33 citation statements)

References 10 publications

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“…Azetidinone thioesters of type 1 are used as key intermediates in the synthesis of penems 2 [l] and were generally made from benzothiazolyldisulfides 3 [2] in two steps: reduction to the corresponding thiol and acylation of the thiol using an activated carboxylic acid. A convenient method for the preparation of thioesters, starting from aryldisulfides using carboxylic acids and tertiary phosphines, was reported by Mukaiyama et al [3].…”

Section: Discussionmentioning

confidence: 99%

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Reactions of Disulfides Derived from Penicillin Sulfoxides with Tertiary Phosphines in Presence of Carboxylic Acids

Prasad¹,

Hamberger²,

Stüutz³

et al. 1981

Helvetica Chimica Acta

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Section: Discussionmentioning

confidence: 99%

“…[2]. Disulfide 12 was prepared from the methyl penicillanate using the procedure of Ernest et al Reactions with disulfide 3.…”

Section: Experimental Partmentioning

confidence: 99%

Reactions of Disulfides Derived from Penicillin Sulfoxides with Tertiary Phosphines in Presence of Carboxylic Acids

Prasad¹,

Hamberger²,

Stüutz³

et al. 1981

Helvetica Chimica Acta

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“…Rf (ethyl acetate) 0.34; [ a ] g = -69f 1" (0.921%, CHC13). 5.62, 5.80, 5.88, 6.15, 6.68, 6.85, 7.11, 7.23, 7.30, 7.69, 8.17, 8.62, 9.02, 9.26, 9.42, 9.94, ,) In principle, the procedure developed by Kamiya et al [7] was used. ,4.97 ,,9.83 ,,11.25 ,,17.19% Disulfide 9.…”

Section: Hetacillin Methyl Ester S-oxide (6)mentioning

confidence: 99%

2‐Oxocephems. II. ‐ synthesis of 2‐oxocephalexin from hetacillin

Ernest

1980

Helvetica Chimica Acta

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2-Oxocephalexin 4, a very labile representative of the novel group of 2-0x0cephem-4-carboxylic acids, has been synthesized from hetacillin.Recently, two different syntheses of (7 R)-7-acylamino-2-oxocephem-4-carboxylic acids 1 have been developed independently in the Bristol Laboratories [l] and in our Institute [2]. Scheme I FOOH RCONH H 0 Q Z 0 Scheme 3 a) 2-Mercaptobenzothiazole, benzene, b) Et3N, CH2C12, RT.: 98%. c) (BOC)20, iPr2NEt, dioxane, 50"; 89%. d) 0 3 , MeOH, -20"; 7231%. e) MeOH, H20, THF, RT.: 86-92% f) NaBH4 or Et4NBH4, DMF etc. reflux; 56-61%.

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“…Further-more, sulfur cyclizations are known to be highly reversible and to give products that can further isomerize. [5,9,13,20] The most widely accepted mechanistic interpretation of sulfur cyclization involves initial generation of a source of a positive sulfur atom (pathway a, Scheme 1), such as sulfanyl halide, followed by intramolecular electrophilic addition of the S atom to the alkene to form episulfonium species. Nucleophilic (S N 2) opening of the episulfonium ion produces the final ring.…”

Section: Introductionmentioning

confidence: 99%

Stereoselective Synthesis of Homochiral Substituted Tetrahydrothiophenes by Electrophile-Promoted Thioetherification

et al. 2003

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In this paper we study the electrophile-promoted cyclization of 2-sulfanyl-4-penten-1-ol and 1-sulfanyl-4-penten-2-ol derivatives as a way of preparing cyclic sulfides. The reaction is completely chemoselective and always proceeds by activation of the sulfur centre. The reaction of 2-sulfanyl-4-penten-1-ol derivatives proceeds by a 5-endo mode. Unsaturated thiol 6 undergoes iodine-promoted cyclothioetherification to give the tetrahydrothiophene 9 in moderate yields and with excellent regio-and stereoselectivity. However, when the reaction starts from the benzyl sulfide 7, a diastereomeric mixture of 9 and 10 is obtained in good yields. Selenium-promoted cyclization of unsaturated thioacetate 5 provides the [a] 209 selenyltetrahydrothiophene 12 or the sulfanyl acetate 13, depending on the selenium reagent used. On the other hand, electrophile-induced cyclization of 1-sulfanyl-4-penten-2-ol derivatives 23−25 depends on the electrophile used. Iodothioetherification of benzyl sulfide 25 followed by oxidation affords unsaturated sulfone 26 as a result of 6-endo-cyclization, dehydroiodination and oxidation. In contrast, selenothiocyclization of 24 with PhSeX results in the formation of the 5-exo tetrahydrothiophenes 29/30 and/or 31/32.

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Studies on β-lactam antibiotics. I. A novel conversion of penicillins into cephalosporins

Cited by 84 publications

References 10 publications

Reactions of Disulfides Derived from Penicillin Sulfoxides with Tertiary Phosphines in Presence of Carboxylic Acids

Reactions of Disulfides Derived from Penicillin Sulfoxides with Tertiary Phosphines in Presence of Carboxylic Acids

2‐Oxocephems. II. ‐ synthesis of 2‐oxocephalexin from hetacillin

Stereoselective Synthesis of Homochiral Substituted Tetrahydrothiophenes by Electrophile-Promoted Thioetherification

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