反应详情

A suspension of 5-nitro-1H-indazole (24.4 g, 150 mmol) and p-TSA (2.58 g, 14.98 mmol) in DCM (1000 mL) was treated with 3,4-dihydro-2H-pyran (41.0 mL, 449 mmol) over 5 min to provide a solution that was stirred at RT for 6 hr. The resulting dark reaction mixture was added to 2 M NaOH (250 mL) and the organic layer was separated, dried and then concentrated in vacuo to afford a black oil. This material was purified by filtering through a plug of silica (˜700 g), loading and eluting with DCM (>12 L) to yield 5-nitro-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole as a pale yellow solid (34.02 g, 133 mmol, 89% yield); Rt 2.06 min, no ionisation observed; 1H NMR (400 MHz, CDCl3) δ: 1.70-1.78 (3H, over-lapping m), 2.14 (2H, m), 2.51 (1H, m), 3.76 (1H, ddd), 4.01 (1H, m), 5.77 (1H, dd), 7.69 (1H, d), 8.21 (1H, d), 8.27 (1H, dd), 8.71 (1H, dd).

1. customto provide a solution that
2. customThe resulting dark reaction mixture
3. customthe organic layer was separated
4. customdried
5. concentrationconcentrated in vacuo
6. customto afford a black oil
7. customThis material was purified
8. filtrationby filtering through a plug of silica (˜700 g), loading
9. washeluting with DCM (>12 L)