Experimental

Titanium tetrachloride (540 µL, 4.95 mmol, 1.1 equiv.) was added to THF (15 mL, 0.3 M) at –78 ºC. This yellow, heterogeneous mixture was warmed to –20 ºC and a solution of LiCl (10 mL, 4.95 mmol, 1.1 equiv., 0.5 M in THF) was added slowly over the course of six minutes. After addition, the mixture was cooled back to –78 ºC and a solution of compound 53 (748 mg, 4.5 mmol, 1.0 equiv.) in THF (6 mL, 0.75 M) was added. The reaction was then warmed to –20 ºC and the stirring was continued. After six hours, the reaction was quenched by pouring into saturated NaHCO₃ (50 mL). The reaction was extracted with Et₂O (3 x 30 mL). The combined organic extracts were washed with brine (50 mL), dried (MgSO₄), and the solvent removed in vacuo to give compound 55 (811 mg, 89%), which was characterized as the crude material due to extreme instability, even upon storage in an inert atmosphere (turns from colorless to black).

Glossary

In vacuo: in a vacuum.

Inert atmosphere: a non-reactive gas atmosphere, often used to store reactive compounds.

References

Richter, J.M.; Ishihara, Y.; Masuda, T.; Whitefield, B.W.; Llamas, T.; Pohjakallio, A.; Baran, P.S. J. Am. Chem. Soc. 2008, 130, 17938-17954.

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