Copper-Impregnated Magnetite as a Heterogeneous Catalyst for the Homocoupling of Terminal Alkynes

The amounts of catalyst and alkyne initially described in the one-pot preparation of 2,5-furans were incorrect. ����

On page 1376, Table 4, the correct scheme and footnote a are:

^a Reaction carried out by using 1 (1 mmol) and H₂O (4 mmol) and under air

On page 1378, the correct 2,5-Furans 3a–d; General procedure is:��

CuO/Fe₃O₄ (5 mg, 0.26 mol%) and t-BuOK (112 mg, 1 mmol) were added to a stirred soln of the appropriate alkyne 1 (1 mmol), and the resulting mixture was stirred at 60 ºC until the reaction was complete (2–7 days; see Table 3). The catalyst was then removed by using a magnet and washed with DMSO (5 mL). The DMSO washings were combined with the original reaction soln, and KOH (280 mg, 5 mmol, 500 mol%) and H2O (4 mmol, 400 mol%) were added under air. The resulting soln was stirred at 80 ºC for 1 day, then the reaction was quenched by addition of H₂O (5 mL). The resulting mixture was extracted with EtOAc (2 × 5 mL) and the combined organic phases were dried (MgSO₄), and concentrated under reduced pressure. The residue was purified by column chromatography.

The authors apologize for this mistake.

Synthesis 2013, 1373.