2345-51-9

• Synthesis of functionalized γ-butyrolactones and tetrahydrofurans via Conia-ene cyclizations.
• Synthesis of allenoates for [2+2] cycloadditions with alkenes.
• Phosphine-catalyzed synthesis of highly functionalized coumarins.
• Synthesis of various useful organotin reagents via radical hydrostannation of 3-butynoic acid.

124-38-9

106-96-7

2345-51-9

Under nitrogen protection, 120 g of 3-bromopropyne was slowly added dropwise to a 1000 ml three-necked flask containing 24 g of magnesium shavings and 300 ml of tetrahydrofuran, and the reaction was carried out for 60 min at room temperature. Subsequently, an excess of carbon dioxide was passed into the reaction system and heated to 60 °C. Upon completion of the reaction, the mixture was poured into cooled 200 ml of saturated aqueous ammonium chloride solution and extracted to separate the organic layer. The organic layer was dried with anhydrous sodium sulfate, filtered and concentrated. The crude product 3-butynoic acid was recrystallized with 50 ml of methyl tert-butyl ether and filtered to obtain crystals. After drying, 70 g of 3-butynoic acid with 98.3% purity was obtained.