Lithium tri-s-butylborohydride → 1-Allyl-1,3,3a,4,5,6,6a,12a-octahydro-7,13-dioxo-1,5-methano-furo[3,4-d]xanthene

To a stirring solution of 1-allyl-1,3,3a,4,5,12a-hexahydro-7,13-dioxo-1,5-methano-furo[3,4-d]xanthene (29.0 mg, 0.0941 mmol) and tetrahydrofuran (15.0 mL) in a dry ice bath under argon was added dropwise 1.0 M L-Selectride in THF (150 μL, 0.150 mmol) and the solution was stirred for 25 min. The dry ice bath was removed and the solution was stirred for 20 minutes. The solution was concentrated by rotary evaporation and was purified by column chromatography (2:1 hexanes/ethyl acetate) to yield 11.4 mg (39%) of the title compound as a white solid. 1H NMR (CDCl3, 300 MHz): δ 7.91 (dd, J1=8.11 Hz, J2=1.79, 1H), 7.54 (ddd, J1=8.17 Hz, J2=6.94, J3=1.45, 1H), 7.08 (m, 2H), 5.86 (m, 1H), 5.27 (m, 1H), 5.12 (dt, J1=10.16 Hz, J2=1.51, 1H), 4.16 (dd, J1=7.97 Hz, J2=4.12, 1H), 3.53 (d, J=7.96 Hz, 1H), 3.40 (dd, J1=11.54 Hz, J2=3.30, 1H), 3.06 (dd, J1=13.46 Hz, J2=6.04, 1H), 2.87 (dd, J1=13.32 Hz, J2=8.93, 1H), 2.82 (dt, J1=14.28 Hz, J2=3.57, 1H), 2.74 (dd, J1=9.89 Hz, J2=4.39, 1H), 2.44 (m, 1H), 2.01 (dd, J1=13.47 Hz, J2=10.44, 1H), 1.78 (ddt, J1=14.15 Hz, J2=11.67 J3=2.68, 1H), 1.67 (dt, J1=14.10 Hz, J2=3.50, 1H).