反应详情

A mixture of the starting material of formula II, tryptophol (500 mg.), levulinic acid (580 mg.), 75 ml. of benzene, 1.7 g. of phosphorus pentoxide and about 0.5 g. of diatomaceous earth (Celite) is stirred magnetically at room temperature for 15 minutes and then at 70° C. for 11/2 hr. The reaction mixture is filtered. The filtrate is washed three times with 5N NaOH; the combined aqueous phase is washed twice with ether and then rendered acidic with cold 50% HCl. The aqueous phase is extracted with chloroform. The chloroform extract is dried (Na2SO4) and evaporated to dryness. The residue is crystallized from ethyl acetate-petroleum ether to afford the title compound, m.p. 104° - 110° C., nmr (CDCl3) δ1.47 (3H), 2.18 (4H), 2.74 (2H), 3.96 (2H), 7.18 (1H), 9.60 (1H).

1. customat 70° C.
2. custom2 hr
3. filtrationThe reaction mixture is filtered
4. washThe filtrate is washed three times with 5N NaOH
5. washthe combined aqueous phase is washed twice with ether
6. extractionThe aqueous phase is extracted with chloroform
7. extractionThe chloroform extract
8. dry with materialis dried (Na2SO4)
9. customevaporated to dryness
10. customThe residue is crystallized from ethyl acetate-petroleum ether