- Direct and practical Gilman-Speeter synthesis of 3,4-trisubstituted β-lactams via the Thorpe-Ingold effect
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A highly efficient Gilman-Speeter synthesis of 3,4-trisubstituted β-lactams possessing a 4-aryl substituent is described, employing a direct, uncatalyzed Mannich reaction between TMS imines and TMS ketene acetals. The process avoids cryogenic conditions, making it more amenable to process-scale use than related methods for β-lactam synthesis. A Gilman-Speeter diastereoselective version using a sulfinyl imine and leading to homochiral sulfinyl β-aminoester is also presented.
- Panagiotou, Maria,Demos, Vasileios,Magriotis, Plato Α.
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- Preparation of β-amino esters and β-lactams from nitriles via aldimine-borane complexes
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A one-pot synthesis of β-amino esters has been achieved in 59-75% yield from aromatic and aliphatic nitriles via the condensation of the corresponding non-enolizable and enolizable aldimine-triethylborane complexes, respectively with methyl trimethylsilyl ketene acetals. Grignard-mediated lactamization of the intermediate β-amino esters provides the corresponding β-lactams in the same pot in 58-74% overall yield. Tha japan Institute of Heterocyclic chemistry.
- Ramachandran, P. Veeraraghavan,Biswas, Debanjan,Chen, Guang-Ming
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experimental part
p. 1423 - 1433
(2011/05/05)
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- Fibrinogen receptor antagonist and pharmaceutical compositions comprising the same
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Compounds of the following general formula (I) and pharmaceutically acceptable salts thereof.
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- Tris(pentafluorophenyl)boron as an Efficient, Air Stable, and Water Tolerant Lewis Acid Catalyst
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Tris(pentafluorophenyl)boron is an efficient, air stable, and water tolerant Lewis acid catalyst for the aldol-type and Michael reactions of silyl enol ethers with carbonyl compounds or other electrophiles (trimethyl orthoformate, dimethal acetal, and chloromethyl methyl ether), the allylation reaction of allylsilanes with aldehydes, and the Diels-Alder reaction of dienes with α,β-unsaturated-aldehydes.A solution of formaldehyde in water is applicable as an electrophile.Also, the aldol-type reaction of ketene silyl acetals with aromatic or aliphatic imines is successfully carried out using the same catalyst.
- Ishihara, Kazuaki,Hanaki, Naoyuki,Funahashi, Miyuki,Miyata, Mayumi,Yamamoto, Hisashi
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p. 1721 - 1730
(2007/10/02)
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- β-Tosylethylamine: A Useful Reagent for Preparation of N-Protected Amides, Carbamates, and Related Compounds. Application to Synthesis of β-Lactams
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Readily prepared β-tosylethylamine (3) can be used to synthesize N-tosylethyl (TSE)-protected amido compounds and β-lactams, which can be deprotected under mild conditions with potassium tert-butoxide.
- DiPietro, Darren,Borzilleri, Robert M.,Weinreb, Steven M.
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p. 5856 - 5857
(2007/10/02)
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- A SYNTHETIC APPROACH TO AZETIDINONES FROM NITRILES AND LITHIUMTRIETHOXYALUMINIUM HYDRIDE.
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A convenient one-pot process for direct conversion of nitriles to 3,4-disubstituted azetidinones has been developed.
- Andreoli, P.,Cainelli, G.,Contento, M.,Giacomini, D.,Martelli, G.,Panunzio, M.
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p. 1695 - 1698
(2007/10/02)
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- Reaction of Silyl Ketene Acetals with N-Trimethylsilyl Imines: a Route to N-Unsubstituted Azetidin-2-ones
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Reaction of N-trimethylsilyl imines with silyl ketene acetals in the presence of ZnI2 and t-butyl alcohol, followed by treatment in situ of the intermediate N-silyl β-aminoesters with MeMgBr, leads to N-unsubstituted azetidin-2-ones in good yield.
- Colvin, Ernest W.,McGarry, Daniel G.
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p. 539 - 540
(2007/10/02)
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- Preparation of Primary Amines and 2-Azetidinones via N-Trimethylsilyl Imines
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Nonenolizable aldehydes react with lithium bis(trimethylsilyl)amide at ambient temperatures to afford solutions of N-trimethylsilyl aldimines.Treatment of these solutions with Grignard reagents or alkyllithiums followed by an aqueous workup gives primary amines in moderate to excellent yields.Treatment of N-trimethylsilyl aldimines with ester enolates provides an expedient route to 1-unsubstituted 2-azetidinones.
- Hart, David J.,Kanai, Ken-ichi,Thomas, Dudley G.,Yang, Teng-Kuei
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p. 289 - 294
(2007/10/02)
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