was added and the mixture was allowed to warm up to 10 °C over 18 h. Afterwards, the mixture was diluted with pentane (500 mL) and filtered through a plug of silica. The silica was thoroughly rinsed with EtOAc:pentane/1:9. The filtrate was concentrated under reduced The dehydrochlorination of allylic chloride S-1 was performed according to a literature known procedure. Freshly ground NaOH (3.57 g, 89.2 mmol, 1.1 equiv.), PPh 3 (1.06 g, 4.05 mmol, 5 mol%) and n-Bu 4 NCl (676 mg, 2.43 mmol, 3 mol%) were loaded into a Schlenk flask. The flask was evacuated and backfilled with argon three times. Afterwards, THF (60 mL) and allylic chloride S-1 (18.7 g, 81.0 mmol, 1.0 equiv.) dissolved in THF (100 mL) were added to the mixture subsequently while keeping the temperature under 25 °C. The mixture was stirred for three days. Afterwards, water (100 mL) was added, the phases were separated and the aqueous phase was extracted with diethyl ether (3 x 100 mL). The combined organic phases were washed with water, brine, dried over Na 2 SO 4 , filtered and concentrated under reduced pressure.