反应详情

To a solution of ethyl 4-(tert-butyldimethylsilyloxy)-2-ethylcyclopentanecarboxylate (0.100 g, 0.333 mmol) in MeCN (2.2 mL) was added triethylsilane (0.080 mL, 0.499 mmol) and bismuth(III) bromide (0.010 g, 0.022 mmol). The reaction mixture was stirred at ambient temperature for about 1 min followed by dropwise addition of dihydro-2H-pyran-4(3H)-one (0.050 g, 0.499 mmol). The reaction mixture was stirred at ambient temperature for about 15 min. The reaction was filtered through an Acrodisc® and the solvent was removed under reduced pressure. To a solution of ethyl 4-(tert-butyldimethylsilyloxy)-2-ethylcyclopentanecarboxylate (0.200 g, 0.666 mmol) in MeCN (4.5 mL) was added triethylsilane (0.160 mL, 1.00 mmol) and bismuth(III) bromide (0.020 g, 0.045 mmol). The reaction mixture was stirred at ambient temperature for about 1 min followed by dropwise addition of dihydro-2H-pyran-4(3H)-one (0.100 g, 0.998 mmol). The reaction mixture was stirred at ambient temperature for about 15 min. The reaction was filtered through an Acrodisc® and the solvent was removed under reduced pressure. The residues were dissolved in DCM (2 mL) each, combined, and the crude material was purified by silica gel chromatography using a gradient of 10-100% EtOAc in heptane to give ethyl 2-ethyl-4-(tetrahydro-2H-pyran-4-yloxy)cyclopentanecarboxylate (0.253 g, 98%) as a colorless oil; 1H NMR (400 MHz, CDCl3) δ 4.13 (q, J=7.1, 2H), 4.05-3.98 (m, 1H), 3.98-3.88 (m, 2H), 3.58-3.47 (m, 1H), 3.46-3.36 (m, 2H), 2.80 (q, J=8.5, 1H), 2.16 (dt, J=13.3, 7.7, 1H), 2.09-1.93 (m, 3H), 1.90-1.81 (m, 2H), 1.62-1.49 (m, 3H), 1.43 (ddd, J=11.1, 7.4, 5.2, 1H), 1.33-1.22 (m, 4H), 0.92-0.83 (m, 3H).

1. stirringThe reaction mixture was stirred at ambient temperature for about 15 min
2. filtrationThe reaction was filtered through an Acrodisc®
3. customthe solvent was removed under reduced pressure
4. stirringThe reaction mixture was stirred at ambient temperature for about 1 min
5. stirringThe reaction mixture was stirred at ambient temperature for about 15 min
6. filtrationThe reaction was filtered through an Acrodisc®
7. customthe solvent was removed under reduced pressure
8. dissolutionThe residues were dissolved in DCM (2 mL) each,
9. customthe crude material was purified by silica gel chromatography