hept-5-ynal

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: At room temp., a piperidinium acetate solution, freshly prepared by mixing piperidine (35.0 μL, 0.354 mmol) and acetic acid (19.0 μL, 0.332 mmol) in dimethyl sulfoxide (1.00 mL), was injected into a stirred solution of the prepared hept-5-ynal (1.50 g, 13.6 mmol) and malonic acid (2.83 g, 27.2 mmol) in dimethyl sulfoxide (50 mL). After refluxing the reaction mixture for 4 h, water (10 mL) and ether (20 mL) were added at room temp., and the layers were separated. The aqueous layer was extracted with ether (3×25 mL), and the combined organic extracts were washed with water (25 mL), dried (Na2SO4), and concentrated under reduced pressure. Kugelrohr distillation at 149° C./14 mbar furnished (3E)-non-3-en-7-ynoic acid (902 mg, 44%) as colorless crystals (mp 43-45° C.). After refluxing the reaction mixture for 4 h the layers were separated The aqueous layer was extracted with ether (3×25 mL) the combined organic extracts were washed with water (25 mL) dried (Na2SO4) concentrated under reduced pressure Kugelrohr distillation at 149° C./14 mbar