Table 1. Copper-Catalyzed Migratory Cycloisomerization Reaction toward Borylated Furans.

entry	substrate	R1, R2	yield, %a (5:6:10)b
1	4a	nBu, H	80 (97:3:0)
2	4b	Ph, H	36 (89:11:0)c
3	4c	2-OMe-Ph, H	51 (99:1:0)
4	4d	2-CF3-Ph, H	96 (0:0:100)d
5	4e	nBu, nBu	0e

^aIsolated yields.

^bNMR ratios.

^cT = 55 °C.

^dHeating of the reaction did not lead to furan.

^eDecomposition of 4.