1-Heptyne → 2-Heptynyl 3-bromothiophene

Participants

Reaction Conditions

Reaction Steps

2 ml (18.0 mmol) of 2,3-dibromothiophene, commercially available from Aldrich under the Product No. D4,390-5, and 3.5 ml (27.0 mmol) of 1-heptyne, commercially available from Aldrich under the Product No. 24, 441-4, were mixed with a solvent of tetrahydrofuran/diisopropylamine (1:1), and 0.23 g (0.36 mmol) of palladium dichlorodiphosphine, 70 mg (0.36 mmol) of copper iodide and 0.1 g (0.36 mmol) of triphenylphosphine were sequentially added thereto. The reaction solution was heated at 70° C. for 8 hours, and washed with an aqueous solution of ammonium chloride. The resulting organic layer was dried over magnesium sulfate, dried under reduced pressure, and purified using silica gel column chromatography, thus obtaining 4.6 g of 2-heptynyl 3-bromothiophene. The compound thus obtained was added with 3.3 ml (23.2 mmol) of trimethylsilylacetylene, commercially available from Aldrich under the Product No. 21, 817-0 and then subjected to the above synthesis process, to prepare 2.7 g (9.84 mmol) of 2-heptynyl-3-trimethylsilylethynylthiophene, which was then mixed with 12.8 ml (12.8 mmol) of lithium diisopropylamide (1 M) at about −78° C. The reaction mixture was stirred at the same temperature for 30 minutes, then combined with 2.4 ml (11.8 mmol) of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, commercially available from Aldrich under the Product No. 41,714-9, and allowed to react in a bath while the temperature was increased to room temperature. The resultant reaction solution was poured into an aqueous solution of 1 N HCl, treated with chloroform to obtain an organic layer, which was then dried over magnesium sulfate 1 N HCl, treated with chloroform to obtain an organic layer, which was then dried over magnesium sulfate and distilled under reduced pressure, thus obtaining 4.1 g of a compound 1a in an oil phase. Analysis of the compound 1a produced the following NMR data: 1H NMR (300 MHz, CDCl3), δ(ppm) 0.24 (s, 9H), 0.92 (t, 3H, J=7.2 Hz), 1.24-1.64 (m, 18H), 2.49 (t, 2H, J=7.0 Hz), 7.47 (s, 1H).

Provenance & Evidence