143159-97-1Relevant academic research and scientific papers
Asymmetric synthesis of 3,4-disubstituted 2-(trifluoromethyl)pyrrolidines through rearrangement of chiral 2-(2,2,2-trifluoro-1-hydroxyethyl)azetidines
Dolfen, Jeroen,Boydas, Esma Birsen,Van Speybroeck, Veronique,Catak, Saron,Van Hecke, Kristof,D'Hooghe, Matthias
, p. 10092 - 10109 (2018/05/31)
Enantiopure 4-formyl-β-lactams were deployed as synthons for the diastereoselective formation of chiral 2-(2,2,2-trifluoro-1-hydroxyethyl)azetidines via trifluoromethylation through aldehyde modification followed by reductive removal of the β-lactam carbonyl moiety. Subsequent treatment of the (in situ) activated 2-trifluoroethylated azetidines with a variety of nitrogen, oxygen, sulfur, and fluorine nucleophiles afforded chiral 3,4-disubstituted 2-(trifluoromethyl)pyrrolidines in good to excellent yields (45-99%) and high diastereoselectivities (dr >99/1, 1H NMR) via interception of bicyclic aziridinium intermediates. Furthermore, representative pyrrolidines were N,O-debenzylated in a selective way and used for further synthetic elaboration to produce, for example, a CF3-substituted 2-oxa-4,7-diazabicyclo[3.3.0]octan-3-one system.
Stereospecific novel glycosylation of hydroxy β-lactams via iodine-catalyzed reaction: A new method for optical resolution
Banik, Bimal K.,Manhas, Maghar S.
, p. 10769 - 10779 (2013/01/15)
Glycosylation of racemic and optically active α-hydroxy β-lactams by reaction with a few glycal derivatives in the presence of catalytic amounts of iodine has provided stereospecific formation of α-glycosides. This method has been extended for the prepara
A β-lactam-based stereoselective access to β,γ-dihydroxy α-amino acid-derived peptides with either α,β-like or unlike configurations
Palomo,Oiarbide,Landa,Esnal,Linden
, p. 4180 - 4186 (2007/10/03)
A concise access to α,β-dihydroxy α-amino acid-derived N-carboxy anhydrides (NCAs) with either like or unlike relative configuration is described. The key steps of the synthetic route are the preparation of the nonracemic 4-alkenyl β-lactams, through either Homer-type olefination of a common 4-formyl β-lactam or the Corey-Winter alkene synthesis applied to 4-dihydroxyalkyl β-lactams, followed by the Sharpless AD reaction, and a subsequent ring expansion of the corresponding 4-substituted 3-hydroxy β-lactams promoted by TEMPO. The opening of thus-prepared NCAs upon treatment with different O- and N-nucleophiles, including α-amino esters which lead to peptides, has also been studied under various reaction conditions.
Base-promoted isomerization of cis-4-formyl-2-azetidinones: Chemoselective C4-epimerization vs rearrangement to cyclic enaminones
Alcaide, Benito,Aly, Moustafa F.,Rodriguez, Carolina,Rodriguez-Vicente, Alberto
, p. 3453 - 3459 (2007/10/03)
Two simple, efficient, and complementary methods for the regiospecific C4-epimerization of cis-4-formyl-2-azetidinones 1-3 are described. The first method uses 40% aqueous dimethylamine as reagent in heterogeneous medium with benzene at room temperature, in the presence of benzyltributylammonium bromide (3-4 mol %) as the phase-transfer catalyst. This transformation tolerates alkyl, alkenyl, alkynyl, aryl, and alkoxy substituents at the C3 of the 2-azetidinone ring. However, limitations of this isomerization are as follows: (i) only N-(p-methoxyphenyl)-β-lactams can be used, and (ii) transformation is less compatible with heteroatomic substituents bonded to the C3 position of the 2-azetidinone ring. A highly general solution to these problems relies on the use of sodium carbonate as the isomerization reagent in different solvents. We also describe a novel base-promoted rearrangement of the β-lactam ring to cyclic enaminones 6 and 21, involving an E1cB-elimination reaction in cis-4-formyl-2-azetidinones.
MICROWAVE-INDUCED ORGANIC REACTION ENHANCEMENT CHEMISTRY. 4 CONVENIENT SYNTHESIS OF ENANTIOPURE α-HYDROXY-β-LACTAMS
Banik, Bimal K.,Manhas, Maghar S.,Kaluza, Zbignew,Barakat, Khaled J.,Bose, Ajay K.
, p. 3603 - 3606 (2007/10/02)
A convenient and rapid synthesis of enantiopure α-hydroxy-β-lactams using microwave-induced organic reaction enhancement chemistry has been developed.Reactions in domestic microwave ovens, which are very convenient and economical for small scale work in research or teaching laboratories, can also be conducted on a preparative scale of 100 - 500 g in simple beakers or flasks. Key Words: α-Hydroxy-β-lactams, microwave-induced organic reactions, enantiospecific synthesis
