To a stirred solution of tert-butyl N-tert-butoxycarbonyl-N-[(3S,7S,8R,9S)-7,8-dihydroxy-9-methyl-2-oxo-1,5-dioxonan-3-yl]carbamate (170 mg, 0.419 mmol), Pd2(dba)3 (38.4 mg, 0.042 mmol) and dppf (46.5 mg, 0.084 mmol) in anhydrous THF (4.0 mL) was added allyl tert-butyl carbonate (332 mg, 2.096 mmol) and the resulting mixture was warmed to 60° C. and stirred for 1 h. The reaction was concentrated and the residue purified by flash chromatography (SiO2, EtOAc/hexanes) to yield the title compound as a light yellow oil (170 mg, 83%): 1H NMR (400 MHz, CDCl3) δ 6.02-5.78 (m, 2H), 5.30-5.10 (m, 5H), 4.81 (dq, J=9.5, 6.3 Hz, 1H), 4.38 (ddd, J=12.2, 5.5, 1.4 Hz, 1H), 4.24 (dd, J=12.1, 4.1 Hz, 1H), 4.17-4.02 (m, 3H), 3.95-3.81 (m, 2H), 3.54 (dd, J=10.9, 7.2 Hz, 1H), 3.41-3.21 (m, 2H), 1.50 (s, 18H), 1.42 (d, J=6.3 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ 169.00, 152.64, 134.93, 134.80, 116.95, 116.78, 84.63, 83.06, 82.84, 75.93, 74.68, 72.85, 72.62, 71.85, 57.94, 27.97, 18.74; ESIMS m/z 509.2 ([M+Na]+).
