Reaktion #42001

Reaktionsgleichung

benzylchloroformate

NaHMDS

β-lactone

(3R, 4R)-3-butyl-4-pentyloxetan-2-one

→

β-lactone

Ausbeute 76.2%

(3S,4S)-benzyl 3-butyl-2-oxo-4-pentyloxetane-3-carboxylate

Ausbeute 76.2%

Lösungsmittel

THF

THF

Reaktionsbedingungen

Vorschrift

To a −78° C. solution of NaHMDS (1.2 equiv, 0.91 mmol, 45 μL, 2M in THF) in 5 mL THF was added 150 mg (0.73 mmol) of β-lactone 3a dissolved in 2.5 mL THF. After 1.5 h, benzylchloroformate (1.1 equiv, 0.833 mmol, 120 μL) was added at one time and stirred for an additional 3 h. This solution was warmed to 23° C. over 1 h and worked up as described above for β-lactone 8b. Flash chromatography on SiO2 (5 % Et2O: hexanes) gave β-lactone 8c (185 mg, 74% yield) as a colorless oil: Rf 0.48 (15% Et2O : Hexanes ); IR (thin film) 1824, 1757, 1716 cm−1; 1H NMR (300 MHz, CDCl3) δ 7.40 (m, 5H), 5.27, 5.22 (AB q, J=12.0, 2H), 4.52 (dd, J=4.8, 8.4 Hz, 11H), 2.50-2.56 (m, 1H), 2.22-2.30 (m, 2H), 1.71-1.85 (m, 1H), 1.44-1.60 (m, 4H), 1.15-1.39 (m, 8H), 0.81-0.92 (m, 6H); 13C NMR (500 MHz, CDCl3) 14, 14.6, 14.7, 23.1, 23.3, 23.6, 24.9, 25.8, 26.9, 29.4, 30.4, 31.1, 31.9, 32.3, 40.4, 71.6, 79.8, 121.7, 129.2, 129.4, 129.5, 129.8, 133.1, 152.7, 163.7, 167.3; ESI LRMS Calcd. for C20H28LiO4+[M+Li]:339. Found: 338.

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