反应详情

A suspension of 6-nitro-2,2,3-trimethyl-3,4-dihydro-2H-1-benzopyran-4-one (40 g, 0.170 mol) in methanol (400 ml) was treated with sodium borohydride (6.4 g, 0.170 mol) at room temperature. After stirring for two hours the solvent was evaporated under reduced pressure, and the residue treated with a mixture of water and dichloromethane. After stirring the organic phase was separated and evaporated under reduced pressure to give 42.2 g of 6-nitro-2,2,3-trimethyl-4-hydroxy-3,4-dihydro-2H-1-benzopyran, as an oil, 1H NMR (CDCl3): δ 1.05 (d, 3H), 1.4 (s, 3H), 1.45 (s, 3H), 2.0-2.2 (m, 2H), 4.4 and 4.9 (multiplets cis and trans, 1H), 6.85 (m, 1H), 8.05 (m, 1H), 8.4 (m, 1H).

1. customwas evaporated under reduced pressure
2. additionthe residue treated with a mixture of water and dichloromethane
3. stirringAfter stirring the organic phase
4. customwas separated
5. customevaporated under reduced pressure