1: ((but-3-ynyloxy)methyl)benzene With n-butyllithium in tetrahydrofuran T=-78°C; 0.333333 h; 2: With boron trifluoride diethyl etherate in tetrahydrofuran T=-78°C; 0.166667 h; 3: ε-caprolactone in tetrahydrofuran T=-78 - 20°C; 1 h;