Tris(2,2,6,6-tetramethyl-3,5-heptanedionato)manganese(III) (281 mg, 0.460 mmol) was dissolved in 2-propanol (100 mL) in a 1 L 3-necked flask equipped with addition funnel, gas inlet, and thermometer. The solution was cooled to −15° C. under nitrogen. Di-tert-butyl azodicarboxylate (8.11 g, 34.5 mmol) and phenylsilane (2.9 mL, 23 mmol) were dissolved in dichloromethane (100 mL) and this resulting orange solution was added to the above cooled solution dropwise over 10 minutes, maintaining the internal temperature at approximately −10° C. A solution of [1.1.1]propellane (Journal of the American Chemical Society (2001), 123(15), 3484-3492) (50 mL, 23 mmol, 0.46 M in pentane) was added to the reaction mixture in one portion at −15° C. The reaction was stirred at −15° C. for 30 minutes. The cold bath was removed and the reaction was allowed to warm to room temperature and stir for 4 hours. The reaction was concentrated and purification by flash column chromatography (5-20% ethyl acetate/heptanes) gave the title compound (6.38 g, 93%) as a clear oil which solidified upon standing. −ESI (M−H) 297.4; 1H NMR (400 MHz, CDCl3, δ): 6.26 (br. s., 1H), 2.37 (s, 1H), 2.02 (s, 6H), 1.45 (s, 18H).
