ethyl cyclobutanecarboxylate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Compound 104b was prepared, likewise the procedure described for 104c, starting from LDA (prepared from BuLi (2.5M in hexanes, 52.8 mL, 132 mmol) and iPr2NH (18.52 mL, 132 mmol, distilled from NaOH)), ethyl 1-cyclobutanecarboxylate (Török, B. et al. J. Chem. Soc. Perkin Trans. 1, 1993, 7, 801-804) (14.05 g, 110 mmol) (the resulting mixture was allowed to warm to 0° C. and cooled again to −60° C.) and 1-bromo-4-chlorobutane (19.1 mL, 165 mmol) to give, after purification by fractional distillation under reduced pressure, 104b (20.53 g, 86%) as a thin, colorless oil. bp: T=64-71° C. (p=0.001 Torr). 1H NMR: δ 4.13 (q, J=7.1 Hz, 2H), 3.51 (t, J=6.8 Hz, 2H), 2.50-2.32 (m, 2H), 1.96-1.70 (m, 8H), 1.40-1.20 (m, 2H), 1.26 (t, J=7.2 Hz, 3H). 13C NMR: δ 176.6, 60.3, 47.6, 44.8, 37.3, 32.8, 30.1 (2×), 22.4, 15.8, 14.4. to give after purification by fractional distillation under reduced pressure, 104b (20.53 g, 86%) as a thin, colorless oil T=64-71° C. (p=0.001 Torr)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: n-Butyl lithium solution (2.20M in hexane, 23.2 ml, 51 mmol) was added via a syringe under nitrogen to a stirred solution of di-i-propylamine (5.13 g, 51 mmol) and HMPA (3.5 ml, 20 mmol) in THF (100 ml) at 0° C. The resulting mixture was stirred at 0° C. for 10 minutes, cooled to -78° C., added a solution of ethyl cyclobutanecarboxylate (5 g, 39 mmol) in THF (10 ml) via a dropping funnel. The resulting mixture was stirred at -78° C. for 0.5 hour, then warmed to 0° C. and stirred for 0.5 hour. The mixture was recooled to -78° C., treated with a solution of benzyl chloromethyl ether (6.58 g, 42 mmol) in THF (10 ml). The resulting mixture was stirred at -78° C. for 20 minutes, slowly warmed to room temperature and stirred for 1 hour. It was poured into cold water, extracted with diethyl ether. The ethereal extract was washed successively with diluted HCl, 5% NaHCO3, dried, filtered and evaporated to give a residue. This residue was purified by distillation to afford the desired product as a pale yellow oil: bp 102°-3° C. (0.02 mm); NMR (CDCl3) δ=1.23 (3H, t, J=7 Hz), 1.6~2.6 (6H, m), 3.68 (2H, s), 4.15 (2H, q, J=7 Hz), 4.53 (2H, s), 7.30 (5H, s). cooled to -78° C. The resulting mixture was stirred at -78° C. for 0.5 hour warmed to 0° C. stirred for 0.5 hour was recooled to -78° C. The resulting mixture was stirred at -78° C. for 20 minutes slowly warmed to room temperature stirred for 1 hour extracted with diethyl ether The ethereal extract was washed successively with diluted HCl, 5% NaHCO3 dried filtered evaporated to give a residue This residue was purified by distillation

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of ethyl cyclobutanecarboxylate (20.0 g, 156.0 mmol) in THF (160 mL) was added dropwise to a cold (−78° C.) solution of LDA (164 mmol of 2M solution) in THF (40 mL). The solution was warmed to 0° C. and then cooled again to −40° C. before the addition of iodomethane (10.2 mL, 163.8 mmol). The solution was slowly warmed to room temperature and stirred overnight. The reaction was quenched with an aqueous saturated solution of ammonium chloride and ether was added. The layers were separated and the aqueous layer was washed with ether. The combined organic layers were washed with 1N HCl then dried over MgSO4. The product was purified by distillation: 1H NMR (400 MHz, MeOD) δ 4.20-4.05 (m, 2H), 2.57-2.33 (m, 2H), 2.08-1.94 (m, 1H), 1.94-1.77 (m, 3H), 1.40 (s, 3H), 1.27 (tt, J=7.1, 1.5 Hz, 3H). The solution was slowly warmed to room temperature The reaction was quenched with an aqueous saturated solution of ammonium chloride and ether was added The layers were separated the aqueous layer was washed with ether The combined organic layers were washed with 1N HCl then dried over MgSO4 The product was purified by distillation

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Compound 104b was prepared, likewise the procedure described for 104c, starting from LDA (prepared from BuLi (2.5M in hexanes, 52.8 mL, 132 mmol) and iPr2NH (18.52 mL, 132 mmol, distilled from NaOH)), ethyl 1-cyclobutanecarboxylate (Török, B. et al. J. Chem. Soc. Perkin Trans. 1, 1993, 7, 801-804) (14.05 g, 110 mmol) (the resulting mixture was allowed to warm to 0° C. and cooled again to −60° C.) and 1-bromo-4-chlorobutane (19.1 mL, 165 mmol) to give, after purification by fractional distillation under reduced pressure, 104b (20.53 g, 86%) as a thin, colorless oil. bp: T=64-71° C. (p=0.001 Torr). 1H NMR: δ 4.13 (q, J=7.1 Hz, 2H), 3.51 (t, J=6.8 Hz, 2H), 2.50-2.32 (m, 2H), 1.96-1.70 (m, 8H), 1.40-1.20 (m, 2H), 1.26 (t, J=7.2 Hz, 3H). 13C NMR: δ 176.6, 60.3, 47.6, 44.8, 37.3, 32.8, 30.1 (2×), 22.4, 15.8, 14.4. to give after purification by fractional distillation under reduced pressure, 104b (20.53 g, 86%) as a thin, colorless oil T=64-71° C. (p=0.001 Torr)