反应详情

Boc-(L)-Ala-(L)-Ala-OMe was prepared as follows. Boc-(L)-Ala-OH (2.06 g, 10.63 mmol) was dissolved in distilled dichloromethane (5 mL). To the resulting solution was added H2N-(L)-Ala-OMe (0.996 g, 9.67 mmol) in 5 mL of distilled dichloromethane. Dicyclohexylcarbodiimide (abbr. DCC; 2.19 g, 10.63 mmol) was dissolved in 3 mL distilled dichloromethane and added to the solution. Dicyclohexylurea (abbr. DCU) precipitation was noted immediately after DCC addition. Triethylamine (3 mL, 21.52 mmol) and additional distilled dichloromethane (4 mL) were added to the reaction mixture. The reaction proceeded for a total of three hours, when TLC analysis indicated consumption of H2N-(L)-Ala-OMe starting material and formation of a new component. DCU precipitation was promoted by storing the reaction at −20° C. The precipitate was filtered through a Buchner funnel and rinsed with cold dichloromethane. The combined filtrate and rinses were dried under vacuum and purified by Silica chromatography to yield dipeptide Boc-(L)-Ala-(L)-Ala-OMe (2.03 g, 7.14 mmol, 74%). 1H-NMR (chloroform-d) δ (ppm): 1.34 (d, J=14.1 Hz, 3H); 1.38 (d, J=14.3 Hz, 3H); 1.40 (s, 9H); 3.73 (s, 3H); 4.14 (s-broad, 1H); 4.55 (quintet, J=14.5 Hz, 1H); 4.97 (s-broad, 1H); 6.59 (s-broad, 1H).

1. distillationdistilled dichloromethane
2. additionadded to the solution
3. customDicyclohexylurea (abbr. DCU) precipitation
4. additionafter DCC addition
5. additionwere added to the reaction mixture
6. customproceeded for a total of three hours, when TLC analysis
7. customconsumption of H2N-(L)-Ala-OMe starting material and formation of a new component
8. customDCU precipitation
9. customthe reaction at −20° C
10. filtrationThe precipitate was filtered through a Buchner funnel
11. washrinsed with cold dichloromethane
12. customThe combined filtrate and rinses were dried under vacuum
13. custompurified by Silica chromatography