277331-22-3Relevant academic research and scientific papers
Optically active 4-formyl β-lactams: Microwave-induced deacetonation-oxidation
Yadav, Ram Naresh,Banik, Indrani,Banik, Bimal Krishna
, p. 1389 - 1391 (2020/06/27)
Microwave-induced chiral synthesis of 4-formyl β-lactams is performed following a one-pot reaction. The deprotection of the ketal with aqueous bismuth nitrate and subsequent oxidation of the diol to aldehyde by aqueous sodium metaperiodate is accomplished
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.
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.
