Synthesis of 3-Amino-2-carboxamide Tetrahydropyrrolo[2,3-b]quinolines

Abstract

All reactions were carried out under a nitrogen atmosphere in dry, freshly distilled solvents unless otherwise noted. All NMR spectra were recorded on a Bruker Avance DRX 400 MHz spectrometer at ambient temperature. Chemical shifts are reported relative to the solvent peak of chloroform (δ 7.26 for 1 H and δ 77.0 for 13 C), DMSO (δ 2.50 for 1 H and δ 39.5 for 13 C), CD 3 OD (δ 3.31 for 1 H and δ 49.00 for 13 C), or acetone (δ 2.05 for 1 H and δ 29.8 for 13 C). 1 H NMR data is reported as position (δ), relative integral, multiplicity (s, singlet; d, doublet; t, triplet; td, triplet of doublets; dd, doublet of doublets; m, multiplet; br, broad peak), coupling constant (J, Hz), and the assignment of the atom. 13 C NMR data are reported as position (δ) and assignment of the atom. All NMR assignments were performed using HSQC and HMBC experiments. High-resolution mass spectroscopy (HRMS) was carried out by either chemical ionization (CI) or electrospray ionization (ESI) on a MicroTOF-Q mass spectrometer. Unless noted, chemical reagents were used as purchased. Experimental Procedures: 2-Azido-N-phenyl acetamide 6a To a solution of bromide 5a (0.80 g, 3.7 mmol) in DMSO (15 mL) under an atmosphere of nitrogen at room temperature was added NaN 3 (0.267 g, 4.1 mmol) and the reaction left to stir for 3 d. Water (30 mL) was then added and the product extracted with ether (3 x 30 mL). The combined organic layers were washed with water (2 x 30 mL) and brine (30 mL), dried (Na 2 SO 4) and the solvent removed in vacuo to give the desired azide 6a (0.658 g, quant.) as a