Reaktion #326217

Reaktionsgleichung

NH4Cl

t-butyl cyclopropanecarboxylate

1,4-dibromobutane

LDA

→

103b

Ausbeute 36.6%

t-Butyl 1-(4-bromo-butyl)-cyclopropanecarboxylate

Ausbeute 36.6%

Lösungsmittel

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigewas allowed to slowly reach rt
2. 2
   SonstigeThe organic layer was separated
3. 3
   Einengenconcentrated in vacuo to a smaller volume
4. 4
   ExtraktionThe aqueous layer was extracted with Et2O (3×200 mL)
5. 5
   WaschenThe combined organic layers were washed with saturated aqueous NH4Cl (2×400 mL) and brine (400 mL)
6. 6
   Sonstigedried
7. 7
   workup.DISTILLATIONThe remaining residue was purified by fractional distillation under reduced pressure

Vorschrift

Under a N2 atmosphere at −60° C., a solution of t-butyl cyclopropanecarboxylate (80.05 g, 0.507 mol) and 1,4-dibromobutane (2193 g, 1.01 mol) in dry THF (800 mL) was added dropwise to a solution of LDA (2 M in THF/heptane/ethylbenzene, 380 mL, 0.76 mol) in 1.5 h. Stirring was continued for 5 h, during which the reaction mixture was allowed to slowly reach rt. After that, the reaction mixture was poured into saturated aqueous NH4Cl (1 L). The organic layer was separated and concentrated in vacuo to a smaller volume. The aqueous layer was extracted with Et2O (3×200 mL). The combined organic layers were washed with saturated aqueous NH4Cl (2×400 mL) and brine (400 mL) and dried. The remaining residue was purified by fractional distillation under reduced pressure to give 103b (51.4 g, 94% pure by GC, 34%) as a slightly yellow oil. bp: T=93-96° C. (p=0.075-0.087 Torr). 1H NMR: δ 3.40 (t, J=6.8 Hz, 2H), 1.85 (quintet, J=7.1 Hz, 2H), 1.65-1.46 (m, 4H), 1.43 (s, 9H), 1.12 (q, J=3.5 Hz, 2H), 0.60 (q, J=3.5 Hz, 2H). 13C NMR: δ 174.0, 79.8, 33.6, 33.2, 32.8, 27.9 (3×), 26.3, 23.9, 15.1 (2×). HRMS calcd for C12H21BrO2 (MH+): 277.0803, found: 277.0807.

Quelle