反应详情

A solution of dicyclohexylacetic acid (4.5 g) in dichloromethane (50 mL) was treated with oxalyl chloride (2.5 mL). Addition of a catalytic amount of N,N-dimethylformamide (1 drop) caused immediate gas evolution to take place. The reaction mixture was stirred for 2 hr, then concentrated to dryness. The residue, consisting of crude dicyclohexylacetyl chloride, was dissolved in acetone (45 mL) and treated at 0° C. with a solution of sodium azide (2.6 g) in water (45 mL). After stirring for 1 hr at 0° C., toluene (100 mL) was added. The organic layer (mainly containing dicyclohexylacetyl azide as shown by IR absorption band at 2128 cm−1) was separated, washed twice with brine, dried (Na2SO4), then heated at reflux for 2 hr. Following evaporation of the solvent, a waxy solid was obtained which mainly consisted of dicyclohexylmethyl isocyanate (IR absorption band at 2275 cm−1). This crude isocyanate was suspended in 20% hydrochloric acid (100 mL) and heated at reflux for 8 h. The insoluble material was filtered off and the filtrate was concentrated in vacuo. The solid residue was taken up in diethyl ether/1N aqueous NaOH and the aqeous layer was re-extracted with ethyl ether. The organic phases were joined and washed with brine, then dried (Na2SO4) and rotoevaporated. The title product was thus obtained as a colourless oil (1.8 g). H1-NMR (200 MHz, DMSO-d6) 0.8-1.8 (m, 22 H); 2.01 (t, 1 H, J=5.4 Hz) ppm.

1. concentrationconcentrated to dryness
2. dissolutionwas dissolved in acetone (45 mL)
3. additiontreated at 0° C. with a solution of sodium azide (2.6 g) in water (45 mL)
4. stirringAfter stirring for 1 hr at 0° C.
5. additiontoluene (100 mL) was added
6. customThe organic layer (mainly containing dicyclohexylacetyl azide as shown by IR absorption band at 2128 cm−1)
7. customwas separated
8. washwashed twice with brine
9. dry with materialdried (Na2SO4)
10. temperatureheated
11. temperatureat reflux for 2 hr
12. customevaporation of the solvent
13. customa waxy solid was obtained which
14. temperatureheated
15. temperatureat reflux for 8 h
16. filtrationThe insoluble material was filtered off
17. concentrationthe filtrate was concentrated in vacuo
18. extractionthe aqeous layer was re-extracted with ethyl ether
19. washwashed with brine
20. dry with materialdried (Na2SO4)