Table 2.

Results of the vinylation reaction of several 5-R-3-iodoindazole derivatives.

Entry	Reactant	R	R′	Heating	Product	Yield a (%)
1	2b	NO2	Boc	µW	3b	13 b
2	1b	NO2	H	µW	3b	87
3	2c	Br	Boc	µW	3c	43 c
4	1c	Br	H	µW	3c	60
5	2d	OCH3	Boc	µW	3d	46 d
6	1d	OCH3	H	µW	3d	58
7	1e	F	H	µW	3e	47
8	1f	Cl	H	µW	3f	60
9	1g	CH3	H	µW	3g	49
10	1h	CN	H	µW	3h	61
11	1i	NHBoc	H	µW	3i	55
12	1j	NH2	H	µW	3j	36 (55) e
13	1a	H	H	conventional	3a	44
14	1b	NO2	H	conventional	3b	21
15	1d	OCH3		conventional	3d	75
16	1e	F	H	conventional	3e	0
17	1g	CH3	H	conventional	3g	17

Reaction conditions: pinacol vinyl boronate (2 eq), Pd(PPh₃)₄ (5–6 mol %), Na₂CO₃ (2N), 1,4-dioxane, µW, 120 °C, 40 min (entries 1–12). Conventional heating, 101 °C, 3 h (entries 13–17). ^a Yields corresponding to the purified products. ^b 3-iodo-5-nitro-1H-indazole was obtained as the major product in 86% yield. ^c 5-bromo-3-vinyl-N-protected derivative was isolated as only coproduct in 5% yield. ^d N-boc-3-vinyl-5-methoxy-1H-indazole was obtained as coproduct in 26% yield. ^e 55% yield for 5-amino-3-vinylindazole 3j corresponds to that obtained by deprotection of 3i.