Triphenylphosphine → (5R,6S,9R)-5-chloro-6-(2,3-difluorophenyl)-9-(triisopropylsilyloxy)-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridine

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Reaction Steps

In an oven-dried 250 mL round-bottom flask was suspended NCS (0.751 g, 5.62 mmol) in tetrahydrofuran (15 mL). Triphenylphosphine (1.475 g, 5.62 mmol) was added. After stirring under nitrogen for 5 min, (5S,6S,9R)-6-(2,3-difluorophenyl)-9-(triisopropylsilyloxy)-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridin-5-ol (1.007 g, 2.250 mmol) was added in one portion to the gray suspension. The resulting reddish suspension was stirred at room temperature. The solids gradually dissolved to give a tan solution. After 5 h, LCMS indicated complete conversion. Tetrahydrofuran was removed in vacuo and the remaining red oil was directly purified by ISCO (240 g silica column) up to 60% ethyl acetate/hexane. Pure ethyl acetate eluted the non polar component and the product was eluted by 10% methanol (with 2.0M NH4OH) in Methylene chloride. The product fractions were combined and re-purified by FCC up to 50% Ethyl acetate/hexane to afford the desired product as a colorless oil (869 mg, 83%).

Provenance & Evidence