- Sterically constrained 'roofed' 2-thiazolidinones as excellent chiral auxiliaries
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The 'roofed' chiral 2-thiazolidinones, which are sterically congested and conformational rigid, and which are prepared by the [4 + 2] cycloaddition of 2-thiazolone to the cyclic dienes, dimethylanthracene and hexamethylcyclopentadiene, followed by optical
- Hoshimoto,Matsunaga,Kunieda
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- Highly stereoselective formal synthesis of rosuvastatin and pitavastatin through Julia-Kocienski olefination using the lactonized statin side-chain precursor
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An expedient and simple synthetic approach to pitava statin and rosuvastatin final intermediates is described. The presented approach consists of completely stereoselective Julia-Kocienski olefination step (E/Z up to 300:1) between lactonized statin side-chain precursor and sulfone derivative of the corresponding pyrimidine and quinoline heterocyclic cores. The desired O-TBS protected statin lactones were isolated in 66-71% yield and high >97% purity (HPLC). Georg Thieme Verlag Stuttgart. New York.
- Fabris, Jan,?asar, Zdenko,Smilovi?, Ivana Gazi?,?rnugelj, Martin
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supporting information
p. 2333 - 2346
(2014/12/09)
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- Hydroxylamine as an oxygen nucleophile: Substitution of sulfonamide by a hydroxyl group in benzothiazole-2-sulfonamides
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Benzothiazole-2-sulfonamides react with an excess of hydroxylamine in aqueous solutions to form 2-hydroxybenzothiazole, sulfur dioxide, and the corresponding amine. Mechanistic studies that employ a combination of structure-reactivity relationships, oxygen labeling experiments, and (in)direct detection of intermediates and products reveal that the reaction proceeds via oxygen attack, and that oxygen incorporated in the 2-hydroxybenzothiazole product derives from hydroxylamine. The reaction, which is performed under mild conditions, can be used as a deprotection method for cleavage of benzothiazole-2-sulfonyl-protected amino acids.
- Kamps, Jos J. A. G.,Belle, Roman,Mecinovi?, Jasmin
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p. 1103 - 1108
(2013/03/28)
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