thionyl chloride 1 h; Cooling with iceReflux;

1.1: 2,2,6,6-tetramethyl-piperidine; n-butyllithium / tetrahydrofuran / 1.5 h / -78 - -30 °C 1.2: 3 h / -78 °C 1.3: 0.33 h / -78 - 20 °C 2.1: borane-THF / tetrahydrofuran / 20 °C / |Cooling with ice 3.1: thionyl chloride / 1 h / |Cooling with ice; |Reflux View Scheme

1: borane-THF / tetrahydrofuran / 20 °C / |Cooling with ice 2: thionyl chloride / 1 h / |Cooling with ice; |Reflux View Scheme