(E)-1-Bromo-4-(2-iodovinyl)benzene → Ethyl 2-(4-bromophenyl)pyrazolo[1,5-a]pyridine-5-carboxylate

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Reaktionsschritte

Related procedures are described in Org. Lett. 2010, 12, 516): 4-Ethoxycarbonyl-N-benzoyliminopyridinium ylid (JOC 2003, 68, 7119) (3.50 g, 13.0 mmol), para-tris-methoxyphenylphosphine (686 mg, 1.95 mmol), Palladium (II) bromide (173 mg, 0.65 mmol), silver triflate (8.93 g, 39.0 mmol) and (E)-1-Bromo-4-(2-iodovinyl)benzene (Org. Lett. 2008, 10, 5485) (4.02 g, 13.0 mmol) were placed in a 250 mL round bottom flask equipped a with magnetic stirrer. Dioxane (52 mL) was added. The mixture was degassed by bubbling nitrogen for 10 minutes with vigorous stirring and heated to 125-130° C. for 15-20 h. The mixture was then cooled to room temperature, diluted with CH2Cl2, filtered over Celite. The organic layer was then washed with saturated aqueous sodium bicarbonate and the organic phase was concentrated under reduced pressure. The crude product was triturated with methanol to afford 2.40 g (54%) of the title compound. LCMS m/z 345.0, 347.0 (M+H)+, ret. time=3.05 min.

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