Synthesis of bi- and tricyclic β-lactam libraries in aqueous medium

Iván Kanizsai, Szilvia Gyónfalvi, Zsolt Szakonyi, Reijo Sillanpää, Ferenc Fülöp
2007 Green Chemistry  
Experimental General 1 H NMR and 13 C NMR spectra were recorded at 400 MHz, in deuteriochloroform at ambient temperature on a Bruker Avance DRX 400 spectrometer. Chemical shifts are given in δ (ppm) relative to tetramethylsilane (deuteriochloroform) as internal standards. Elemental analyses were performed with a Perkin-Elmer CHNS-2400 Ser II Elemental Analyzer. IR spectra were measured on a Perkin-Elmer model 1000 FT-IR spectrophotometer. Melting points were determined on a Kofler apparatus and
more » ... ofler apparatus and are uncorrected. The anisaldehyde was freshly distilled for the reactions. General Procedure for the Preparation of β-Lactams (2a-q) To the β-amino acid (I-VIII) (1.1 mmol) dissolved in a few drops of water, the corresponding aldehyde (A-D) (1.0 mmol) was added dropwise. Further water was then cautiously added dropwise until the generated Schiff base just dissolved. The reaction mixture was stirred for 1 h at room temperature, followed by addition of the isocyanide (a, b) (1.0 mmol). The resulting mixture was stirred for 1 day at room temperature. The precipitate (2j, 2l and 2p) was then filtered off. When the product did not precipitate, evaporation of the aqueous solution in vacuo resulted in 2a, 2c-e, 2g-i, 2n and 2o in higher than 85% purity. For 2b, 2f, 2k, 2m, and 2q, the β-lactams were obtained as solids and were crystallized from EtOH/EtOAc. N-Cyclohexyl-2-(7-oxo-6-azabicyclo[3.2.0]hept-6-yl) butyramide (2a)
doi:10.1039/b613117d fatcat:zdnvvwcymfhf5brf6rsx2dti7m