Basicity‐Controlled [3+2] Cyclization of 3‐Hydroxyquinolin‐ones and β‐Chlorinated Nitrostyrenes

Abstract

The construction of novel skeletons through the recombination of natural products ring systems is attractive. Herein, a basicity‐controlled synthesis of (dihydro)furo[2,3‐c]quinolin‐4(5H)‐one derivatives through (3+2) cyclization between 3‐hydroxyquinolin‐2‐ones and β‐chlorinated nitrostyrenes was developed. In addition, preliminary study gave the chiral dihydrofuro[2,3‐c]quinolin‐4(5H)‐one derivatives with up to 83 % ee.

Bromonitroalkenes as efficient intermediates in organic synthesis

“…Very recently, Wu and coworkers investigated the reaction of 3-hydroxyquinolin-2-ones 52 with β-chlorinated nitrostyrenes 43 for the synthesis of (dihydro)furo[2,3- c ]quinolin-4(5 H )-one derivatives 53 and furo[2,3- c ]quinolin-4(5 H )-one derivatives 54 (Scheme 25). 29 The reaction is under the control of the base. Under a catalytic amount of DIPEA (20 mol%) and 2 equivalents of Na 2 CO 3 in acetone, the products 53 were obtained in 48–81% yields and >20 : 1 diastereoselectivities.…”