1-Butyl 1-[9-[1-(tert-butoxycarbonyl)cyclopropyl]-5-oxononyl-1-cyclopropanecarboxylate (106d). Under a N2 atmosphere, NaH (60% (w/w) in mineral oil, 2.91 g, 72.8 mmol) was added portionwise to a solution of TosMIC (5.85 g, 30.0 mmol) and Bu4NI (1.10 g, 2.98 mmol) in dry DMSO (100 mL) while stirring vigorously and cooling with a water bath. After 10 min, 103b (16.56 g, 94% pure by GC, 56.2 mmol) was added dropwise in 20 min and stirring was continued for 1 h and 50 min. Then, H2O (100 mL) was added dropwise and the resulting mixture was extracted with Et2O (3×100 mL). The combined organic layers were washed with brine (2×100 mL) and dried. The remaining oil was purified by column chromatography (silica, heptane:EtOAc=6:1) to give t-butyl 1-{9-[1-(t-butoxycarbonyl)cyclopropyl]-5-isocyano-5-[(4-methylphenyl)sulfonyl]nonyl}-1-cyclopropanecarboxylate (10.00 g) as a slightly yellow oil.
