Hydrochloric Acid → 3,4-Dimethylthiophene-2-carbaldehyde

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Reaction Steps

A solution of 1.5 M n-butyllithium (3.4 mL, 5.1 mmol) in ether was added dropwise under argon to a solution of 3,4-dimethylthiophene trimer (1.62 g, 4.8 mmol, See Example 16) in dry THF (10 mL) at −70° C. and the resultant solution was warmed to −50° C. Next, 0.4 mL (5.4 mmol) of DMF was added dropwise and the mixture allowed to warm to room temperature overnight. The mixture was poured into a mixture of 1 liter of 12 M HCl and crushed in certain embodiments and thereafter extracted with ether. The organic layers were combined, washed with water, and dried over MgSO4. After evaporation of the solvent, the residue was purified by column chromatography (silica gel, hexane/CH2Cl2 (v:v) 3:1) to give the product 2-formyl-3,4-dimethylthiophene as a yellow solid (0.98 g, 56%) and recovered unreacted trimer (0.55 g). 1H NMR (CDCl3) δ 10.08 (1H, s, CHO), 6.99 (1H, s, aromatic H), 2.53 (3H, s, CH3), 2.22 (3H, s, CH3), 2.16 (3H, s, CH3), 2.13 (3H, s, CH3), 2.10 (6H, s CH3).

Provenance & Evidence