Reaction Steps
To a round-bottom flask equipped with a stir bar was added tert-butyl ((2S,3S)-3-((R)-hex-5-en-2-yloxy)-1-((2S,4R)-4-hydroxy-2-(((1R,2S)-1-(((1-methylcyclopropyl)sulfonyl)carbamoyl)-2-vinylcyclopropyl)carbamoyl)pyrrolidin-1-yl)-1-oxopentan-2-yl)carbamate (all material from step 4, 569 mg, 0.869 mmol) and DCE (100 mL). The solution was sparged with nitrogen for 30 min. and then to the solution was added (1,3-Bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene)dichloro(o-isopropoxyphenylmethylene)ruthenium (“Hoveyda-Grubbs Catalyst 2nd Generation”, 27 mg, 0.043 mmol). The solution was stirred at 80° C. for 2 h and then cooled to 45° C. and stirred for 3 days. The solution was concentrated in vacuo and the resulting residue was subjected to silica gel purification (hexanes:acetone 80:20 to 40:60). The product containing fractions were pooled; concentrated; and re-subjected to silica gel chromatography (hexanes:acetone 80:20 to 40:60) to afford tert-butyl ((2R,6S,7S,9R,13aS,14aR,16aS,Z)-7-ethyl-2-hydroxy-9-methyl-14a-(((1-methylcyclopropyl)sulfonyl)carbamoyl)-5,16-dioxo-2,3,5,6,7,9,10,11,13a,14,14a,15,16,16a-tetradecahydro-1H-cyclopropa[i]pyrrolo[1,2-e][1,5,8]oxadiazacyclopentadecin-6-yl)carbamate as a light-brown solid foam (90 mg, 10% over 5 steps). 1H-NMR (500 MHz, CD3OD) δ 8.93 (s, 1H), 5.61 (td, J=10.1, 6.2 Hz, 1H), 5.03 (t, J=10.3 Hz, 1H), 4.58 (br. s., 1H), 4.47-4.37 (m, 2H), 3.92 (br. s., 2H), 3.86-3.79 (m, 1H), 3.58-3.49 (m, 1H), 2.75 (q, J=9.5 Hz, 1H), 2.64-2.52 (m, 1H), 2.23-2.11 (m, 2H), 1.92-1.80 (m, 2H), 1.75 (dd, J=8.5, 5.5 Hz, 1H), 1.66-1.60 (m, 1H), 1.59-1.52 (m, 2H), 1.49 (s, 4H), 1.43 (s, 9H), 1.41-1.32 (m, 2H), 1.15 (d, J=6.3 Hz, 3H), 0.95 (t, J=7.4 Hz, 3H), 0.88-0.84 (m, 2H).
