Dimethyl Sulfoxide → 6-(1,1-Dimethylethyl) 1-ethyl 6-azaspiro[2.5]octane-1,6-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

Sodium hydride (60% in mineral oil) (2.06 g, 85.8 mmol) was added to dimethylsulfoxide (100 mL) at 15° C., and the mixture was stirred at 15° C. for 20 min. See FIG. 6. Trimethylsulfoxonium iodide (19.0 g, 85.8 mmol) was added, and the reaction mixture was stirred for 2 h, then 165b (7.72 g, 28.7 mmol) was added and the resulting mixture was stirred at 15° C. for 50 h. Water (100 mL) was added, and the mixture was extracted with EtOAc (200 mL×3). The combined organic extracts were washed with brine (100 mL×2), dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by silica gel column (petroleum ether: EtOAc=2:1) to yield 6-tert-butyl 1-ethyl 6-azaspiro[2.5]octane-1,6-dicarboxylate 165c (4.4 g, 54%) as a colorless oil. 1H NMR (400 MHz, CD3CN): δ 4.06-4.04 (m, 2H), 3.40-3.18 (m, 4H), 1.92-1.90 (m, 1H), 1.59-1.50 (m, 3H), 1.39-1.30 (m, 10H), 1.19-1.16 (m, 3H), 1.03-1.01 (m, 1H), 0.91-0.93 (m, 1H).

Provenance & Evidence