Tin tetrachloride → 2-[2-(2-thienylcarbonyl)-1H-pyrrol-1-yl]-1H-isoindole-1,3(2H)dione

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Reaction Steps

A solution of 2-thiophenecarbonylchloride (10.7 ml) in 500 ml of dry DCM was treated at -10° C. with tin tetrachloride (11.7 ml) and stirred for 30 minutes. 2-(1H-pyrrol-1-yl)-1H-isoindole-1,3(2H)dione (21.2 g) was then added in small portions over a period of 30 minutes at -10° C. After the addition was completed, the reaction mixture was stirred for an additional 30 minutes at -10° C. and subsequently poured into 500 ml of ice water. The precipitate was dissolved by addition of about 1000 ml of DCM and the separated aqueous layer extracted again with DCM. The combined organic layers were washed twice with 2N hydrochloric acid and with water, dried over magnesium sulfate and evaporated in vacuo. The residue was purified by flash column chromatography (silica gel, DCM/ethyl acetate 99:1) and the desired fractions were concentrated. The residue was recrystallized from DCM/ethyl ether affording the product as crystals (17.9 g), m.p. 165°-166° C.

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