Methanol → Tert-butyl (s,s)-3,3-dimethyl-3-silabutyl 2-(4-((tert-butyl)oxycarbonyl)-2-(2-bromoacetylamino) butanoylamino)pentane-1,5-dioate

Participants

Reaction Steps

The product of step 7H (397 mg, 0.813 mmol) was dissolved in dry tetrahydrofuran (5 mL) with diisopropylethylamine (180 μL, 1.05 mmol) and cooled to —10° C. under nitrogen. Bromoacetyl bromide (85 μL, 0.98 mmol), dissolved in 10 mL tetrahydrofuran, was added dropwise to the cold solution, keeping T≦−5° C. The reaction was stirred in the cold for 1.5 hr, and 25 μL methanol added. The solids were filtered and rinsed and the combined filtrate concentrated to a brown oil, which was purified by flash chromatography (dichloromethane/ethyl acetate) to afford the product (388 mg, 78%) as a light tan oil. LRMS (ES): 609.3/611.3 [M+H]+, 631.3/633.3 [M+Na]+, 185.3, 144.2. 1HNMR (600.1343 MHz, CDCl3): 7.32 (m, 1H), 7.09 (m, 1H), 4.50 (m, 2H), 4.21 (m, 2H), 3.87 (m, 2H), 2.31 (m, 2H), 2.13 (m, 2H), 1.99 (m, 2H), 1.97 (m, 2H), 1.45 (s, 9H), 1.43 (s, 9H), 1.01 (m, 2H), 0.04 (s, 9H).

Provenance & Evidence