Triethylamine → tert-butyl 4-[(E)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)but-3-enyl]-4,9-diazaspiro[5.5]undecane-9-carboxylate

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Reaction Conditions

Reaction Steps

Triethylamine (5.62 mmoles; 0.783 mL), 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (8.56 mL, 59.0 mmol) and zirconocene chloride (1.45 g, 5.62 mmoles) are added to tert-butyl 4-but-3-ynyl-4,9-diazaspiro[5.5]undecane-9-carboxylate (17.21 g, 56.16 mmoles). The resulting mixture is heated to 65° C. for 3.5 hours. The mixture is cooled and dissolved in dichloromethane (150 mL). The resulting solution is passed through a ˜4 cm thick pad of silica gel, eluting with dichloromethane (2×200 mL). The filtrate is concentrated under reduced pressure to give the title compound (21.2 g, 87% yield). 1H NMR (300.11 MHz, CDCl3): δ 6.65-6.55 (m, 1H), 5.49-5.43 (m, 1H), 3.42-3.29 (m, 4H), 2.40-2.27 (m, 6H), 2.25-2.08 (m, 2H), 1.70-1.13 (m, 29H).

Provenance & Evidence