1.1: 2,2,6,6-tetramethyl-piperidine; n-butyllithium / tetrahydrofuran; hexane / 2 h / -78 °C / |Inert atmosphere 1.2: 0.5 h / -78 °C 2.1: borane-THF / tetrahydrofuran / 24 h / 0 - 20 °C / |Inert atmosphere 2.2: 6 h / 60 °C 3.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 0.5 h / 20 °C View Scheme

1.1: 2,2,6,6-tetramethyl-piperidine; n-butyllithium / tetrahydrofuran; hexane / 2 h / -78 °C / |Inert atmosphere 1.2: 0.5 h / -78 °C 2.1: borane-THF / tetrahydrofuran / 24 h / 0 - 20 °C / |Inert atmosphere 2.2: 6 h / 60 °C 3.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 0.5 h / 20 °C 4.1: potassium carbonate / N,N-dimethyl-formamide; acetone / 5.5 h / 20 °C View Scheme

1.1: BuLi; 2,2,6,6-teramethylpiperidine / tetrahydrofuran; hexane / 2 h / -75 °C 1.2: tetrahydrofuran; hexane 2.1: 3.87 g / TBAF / tetrahydrofuran / 2 h / 25 °C View Scheme