“…t-BuLi (1.4 M in ether, 0.437 mL, 0.61 mmol) was added to a solution of complex la (160 mg, 0.51 mmol) in THF (5 mL) at -78 °C. The solution was slowly warmed to -20 °C over 3 h. After recooling, oxidation, and workup, GC analysis showed a single product and unreacted 4a (initial T 100 °C, initial time 5 min, 20 °C/min; Rf 13.6 min). Purification by flash chromatography (Si02,5/1 hexane/ether) afforded 35 mg (30%) of 39a, with a slight impurity of 4a.…”