- A Novel Synthesis of the Monobactam Antibiotic Carumonam
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A novel synthesis of the monobactam 4, a precursor of the antibiotic carumonam (3), has been achieved via the epoxide methyl (2R,3S)-4-acetoxy-2,3-epoxybutyrate (10).The latter was prepared from calcium L-threonate in three steps and 85percent overall yield.In a related study, ethyl (2R,3S)-4-hydroxy-2,3-epoxybutyrate (17) was prepared from L-(+)-tartaric acid in 45percent overall yield.Treatment of the sodium salt derived from 10 or 17 with ammonia led to a stereo- and regiospecific opening of the oxirane ring to give 20, after esterification, amide formation, and protection of the amino group.Conversion of 20 into 4 was accomplished by selective protection of the primary hydroxy group with chloroacetyl chloride, mesylation, sulfonation with 2-picoline-SO3, and ring closure with potassium bicarbonate.
- Manchand, Percy S.,Luk, Kin-Chun,Belica, Peter S.,Choudhry, Satish C.,Wei, Chung Chen,Soukup, Milan
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p. 5507 - 5512
(2007/10/02)
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- Insertion of Sulfur Trioxide into the N-Si bond of Anilinotrimethylsilane. An Improved Method for the Preparation of Free Phenylamidosulfuric Acid
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The reaction between anilinotrimethylsilane (1) and a variety of sulfonating agents has been studied.With SO3, 5, or a dioxane-sulfur trioxide complex a sulfur trioxide molecule was inserted selectively into the N-Si bond of 1 to yield trimethylsilyl phenylamidosulfate (2), which on treatment with acetic acid, trifluoroacetic acid, or methanol gave free phenylamidosulfuric acid (3).The reaction of 1 with ClSO3H afforded 3 directly, but the product was contaminated with slight amounts of anilinium hydrogensulfate and anilinium chloride.The reaction of 1 with 10 yielded a mixture containing dianilinium (4-sulfonatophenylamido)sulfate, 4-aminobenzenesulfonic acid, and ethyl phenylamidosulfate as major products (after desilylation).The reaction of 1 with 5 has been found to provide an improved method for preparing 3.
- Kanetani, Fujio,Okada, Eiji,Negoro, Kenji
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p. 2517 - 2520
(2007/10/02)
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- UBER PEROXOVERBINDUNGEN 17 DARSTELLUNG UND EIGENSCHAFTEN VON ALKYL- UND TRIMETHYLSILYLDERIVATEN VON PEROXOSCHWEFELSAEUREN
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The novel peroxides Me3SiOSO2OOR (3; R = n-C3H7, n-C4H9, n-C5H11), Na+-OSO2OOR (5; R = n-C3H7, n-C4H9), and HOSO2OOR (6; R = n-C3H7, n-C4H9) are obtained by insertion of SO3 in Me3SiOOR, NaOOR, and HOOR respectively (temperature below -20 deg C, solvent CH2Cl2).The solid compounds 5 are stable up to 40-50 deg C, the liquids 3 and 6 deflagrate at ca. -10 deg C.Hydrolysis of the sulfonyl peroxides generates HOOR in each case.Thermolysis of 3 affords the corresponding aldehydes by heterolysis of the (O-O)-bond.In CH2Cl2 at room temperature, Me3SiOSO2OOSiMe3 (1) undergoes a slow nucleophilic 1,2-rearrangement, forming the isomer Me3SiOSO2OSi(OMe)Me2 (7).The constitution of 7 is confirmed by chemical evidence, e. g. hydrolytic and thermal degradation.Thermolysis of Me3SiOSO2OOSO2OSiMe3 (2) at room temperature in CH2Cl2 occurs by a rather rapid free radical pathway, the solvent being attacked by H and/or Cl abstraction (main products: HCl, CO, ClSO2OSiMe3, Me3SiOSO2OSiMe3).The new trimethylsilyl(n-alkyl)-peroxides Me3SiOOR with R = n-C3H7, n-C4H9, and C5H11 were prepared and characterised.
- Blaschette, Armand,Safari, Hassan
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