Synthesis of Pyrazolo[4,3‐c]quinolines from Morita–Baylis–Hillman Adducts of 2‐Bromobenzaldehydes

Abstract

The synthesis of pyrazolo [4,3-c]quinolines has been carried out from the Morita-Baylis-Hillman bromides of 2-bromobenzaldehydes and methyl vinyl ketone. The synthesis involved a novel one-pot preparation of functionalized pyrazoles from α,β-enones, a one-pot Cu-mediated intramolecular N-arylation, and the elimination of p-toluenesulfinic acid.Compound 2e: 63%; white solid, m.p. 166-168 C; IR (KBr) 3274, 1502, 1327, 1161 cm −1 ; 1 H NMR (CDCl 3 , 300 MHz) δ 1.28 (t, J = 7.5 Hz, 3H), 2.41 (s, 3H), 2.66 (q, J = 7.5 Hz, 2H), 3.74 (dd, J = 12.9 and 4.5 Hz, 1H), 3.91 (dd, J = 12.9 and 6.6 Hz, 1H), 4.28 (dd, J = 6.6 and 4.5 Hz, 1H), 7.04-7.09 (m, 1H), 7.12-7.27 (m, 9H), 7.47-7.52 (m, 1H), 7.62 (d, J = 8.4 Hz, 2H); 13 C NMR (CDCl 3 , 75 MHz) δ