644995-89-1Relevant academic research and scientific papers
Comparartive Study on the Reactivity of 6-Haloimidazo[1,2-a]pyridine Derivatives towards Negishi- and Stille-Coupling Reactions
Hervet, Maud,Thery, Isabelle,Gueiffier, Alain,Enguehard-Gueiffier, Cecile
, p. 3461 - 3469 (2003)
The scope of the Suzuki-cross-coupling reaction of 6-haloimidazo[1,2-a]pyridines is dependent on the availability of the (hetero)arylboronic acids. Thus, with the aim to develop expanded applications of (hetero)arylations of imidazo[1,2-a]pyridines, we investigated the Negishi- and Stille-cross-coupling reactions at the 6-position. Remarkably, attempts to aply the Negishi-cross-coupling conditions to the organozinc derivative prepared from 6-haloimidazo[1,2-a]pyridine via a lithium-zinc exchange led to the 5-phenyl compound 3 in 54 percent yield instead of the desired 6-phenyl-isomer (Scheme 1). In contrast, various commercially available halogenated five- or six-membered-ring heterocycles were efficiently coupled to the 6-(trialkylstannyl)imidazo[1,2-a]pyridine under Stille conditions (Table 2).
