1: triethyl-ethynyl-silane With n-butyllithium in tetrahydrofuran; hexane T=-78 - 0°C; 0.666667 h; 2: N,O-dimethylacetohydroxamic acid in tetrahydrofuran; hexane T=-78 - -10°C;

manganese(IV) oxide in dichloromethane Inert atmosphere;

1.1: n-butyllithium / tetrahydrofuran; hexane / 1 h / -50 °C / |Inert atmosphere; |Schlenk technique 1.2: -50 - 20 °C / |Inert atmosphere; |Schlenk technique 2.1: BaMnO4 / dichloromethane / 20 °C / |Inert atmosphere; |Schlenk technique View Scheme