反应详情

1.63 g of tert-butyl trans-4-hydroxycyclohexanecarboxylate (8.14 mmol, 1 eq.) and 1.62 g of ethyl 6-hydroxynicotinate (10.58 mmol, 1.3 eq.) are placed in 24 mL of tetrahydrofuran at room temperature. 3.20 g of triphenylphosphine (12.21 mmol, 1.5 eq.) are added, followed by dropwise addition of 2.37 mL of diisopropyl azodicarboxylate (12.21 mmol, 1.5 eq.) to the reaction medium with stirring. After 1 hour at room temperature, the medium is concentrated to dryness and taken up in diethyl ether. The triphenylphosphine oxide is filtered off. The organic phase is washed successively with sodium hydroxide solution and than with water, dried over magnesium sulfate, filtered and evaporated to give a residue. This residue is chromatographed on silica gel, eluting with a gradient of ethyl acetate in heptane ranging from 3% to 30%. 1.3 g of ethyl cis-6-(4-tert-butoxycarbonylcyclohexyloxy)-nicotinate are obtained.

1. concentrationthe medium is concentrated to dryness
2. filtrationThe triphenylphosphine oxide is filtered off
3. washThe organic phase is washed successively with sodium hydroxide solution and than with water
4. dry with materialdried over magnesium sulfate
5. filtrationfiltered
6. customevaporated
7. customto give a residue
8. customThis residue is chromatographed on silica gel
9. washeluting with a gradient of ethyl acetate in heptane ranging from 3% to 30%