toluene-4-sulfonic acid in methanol T=50°C;

1: dimethyl(1,1-dimethylethyl)(2-propynyloxy)silane With n-butyllithium in tetrahydrofuran T=-78°C; 2: 4-methyl-[1,3,2]dioxathiolane 2,2-dioxide in tetrahydrofuran T=-78 - 20°C;

1: 2-(2-propynyloxy)-tetrahydro-2H-pyran With n-butyllithium in tetrahydrofuran T=-78°C; 2: 4-methyl-[1,3,2]dioxathiolane 2,2-dioxide in tetrahydrofuran T=-78 - 20°C;