A novel copper-catalyzed, hydrazine-free synthesis of N-1 unsubstituted 1H-indazoles using stable guanylhydrazone salts as substrates

Efficient approach to 1,1′-bisindoles via copper(i)-catalyzed double domino reaction

“…Based on our experience with Cu( i )-catalyzed reactions for the synthesis of heterocycles 38–46 and the results of other groups concerning the Cu( i )-catalyzed synthesis of indoles 47,48 we decided to react 1,2-bis(2-bromophenyl)hydrazine ( 1a ) with an excess of 4 equiv. of acetylacetone ( 2a ) in the presence of 2 equiv.…”

LiBF4-Promoted Aromatic Fluorodetriazenation under Mild Conditions

“…6-Fluoro-1H-indazole (3zg). 33 Following general procedure A and purification by flash chromatography (silica gel, from 100:0 to 90:10 petroleum ether/ethyl acetate), compound 6a was obtained as an offwhite solid (58 mg, 0.43 mmol, 86%). 1 H NMR (400 MHz, DMSOd 6 ) δ 13.13 (s, 1H), 8.08 (s, 1H), 7.79 (dd, J = 8.8, 5.3 Hz, 1H), 7.31 (dd, J = 9.7, 2.3 Hz, 1H), 6.99 (td, J = 9.2, 2.2 Hz, 1H); 19 F NMR (376 MHz, DMSO-d 6 ) δ −115.9.…”