Hydrochloric Acid → 4H,5H,6H-thieno[2,3-c]pyrrol-6-one

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Reaction Conditions

Reaction Steps

A 250-mL single-neck round-bottomed flask equipped with a magnetic stirrer was purged with nitrogen and charged with 116d (5.00 g, 29.2 mmol) and THF (150 mL). Bis(trimethylaluminum)-1,4-diazabicyclo[2.2.2]octane complex (10.0 g, 39.1 mmol) was added portionwise. The mixture was heated at 60° C. for 14 h. After this time, the mixture was cooled to 0° C. 4 M hydrochloric acid (60 mL) was added dropwise, and the mixture was filtered. The organic layer was separated, and the aqueous layer was extracted with a 20% (v/v) solution of methanol in methylene chloride (3×150 mL). The filter cake was washed with a 20% (v/v) solution of methanol in methylene chloride (3×150 mL). The combined organic layers were dried over sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography (silica, 0% to 10% methanol/methylene chloride) to afford a 45% yield (1.87 g) of 116e as an off-white solid: mp 104-105° C.; 1H NMR (300 MHz, CDCl3) δ 7.08 (s, 1H), 6.42 (br s, 1H), 4.37 (s, 2H); MS (ESI+) m/z 140.0 (M+H).

Provenance & Evidence