Scheme 5.
Synthesis of benzofuran analoguesa
R1 = phenyl (16a), cycloheptyl (16b), isopropyl (16c), butyl (16d), cyclohexyl (16e), cyclopentyl (16f)
aReagents and Conditions: (a) R1NH2, ZnCl2, NaCNBH3, r.t., 2 h; (b) 3,4-dimethoxybenzenesulfonyl chloride, Et3N, DCM, r.t., 14 – 42%.