Synthesis of chromeno[4,3-b]quinolines and spirobenzofuran-3,3′-quinolines through silver-mediated Appel reaction/C–Br bond cleavage/double selective rearrangement sequence†
Hong-Ping Zhao,Xiao-Pan Ma,Shu-Min Nie,Yuhong Xiao,Dong-Liang Mo
Organic Chemistry Frontiers Pub Date : 05/06/2019 00:00:00 , DOI:10.1039/C9QO00417C
Abstract

Various chromeno[4,3-b]quinolines and spirobenzofuran-3,3′-quinolines were prepared in good to excellent yields through a reduction and silver-mediated Appel reaction/sequential C–Br bond cleavage/double selective rearrangement cascade strategy from easily available chromeno[4,3-b]indolecarbaldehydes. Cross-over experiments revealed that the group migration occurred intramolecularly and the electronic effect on styrenyl groups had a little effect on the migration step. Two novel quinoline scaffolds were easily prepared on a gram scale by simple operation.

Graphical abstract: Synthesis of chromeno[4,3-b]quinolines and spirobenzofuran-3,3′-quinolines through silver-mediated Appel reaction/C–Br bond cleavage/double selective rearrangement sequence