Реакция #1117704

Уравнение реакции

tetra-n-butylammonium fluoride

t-butoxycarbonyl-L-leucinal

2-trimethylsilyl thiazole

→

(S)2-(t-butoxycarbonyl)amino-4-methyl-(S)1-(2-thiazolyl)pentan-1-ol

Выход 4.6%

Растворители

tetrahydrofuran

dichloromethane

dichloromethane

Условия реакции

Обработка

1. 1
   Температураwas cooled in an ice bath
2. 2
   ТемператураThis mixture was refluxed for 1.5 hours
3. 3
   Концентрированиеconcentrated to an oil
4. 4
   workup.DISSOLUTIONThe oil was dissolved in 100 ml of ethyl acetate
5. 5
   Промывкаwashed with 50 ml each of 2N citric acid, 1M sodium bicarbonate and brine
6. 6
   Другоеdried
7. 7
   workup.ADDITIONThe solution was treated with activated carbon
8. 8
   Фильтрацияfiltered through a pad of hydrous magnesium silicate
9. 9
   Концентрированиеconcentrated to an oil
10. 10
    workup.DISSOLUTIONThis oil was dissolved in 50 ml of 10% ethyl acetate in dichloromethane
11. 11
    Другоеchromatographed on two columns in the same solvent
12. 12
    Другоеwere separately evaporated
13. 13
    ДругоеThe first three of these all crystallized
14. 14
    Другоеthe solids were recrystallized form isopropyl ether and hexane

Методика

To a solution of 10.8 g of t-butoxycarbonyl-L-leucinal in 40 of dichloromethane was added 9.4 g of 2-trimethylsilyl thiazole in 10 ml of dichloromethane. The reaction was allowed to stand for 48 hours, then was cooled in an ice bath and treated cautiously with 30 ml of 1M tetra-n-butylammonium fluoride in tetrahydrofuran. This mixture was refluxed for 1.5 hours and then concentrated to an oil. The oil was dissolved in 100 ml of ethyl acetate, washed with 50 ml each of 2N citric acid, 1M sodium bicarbonate and brine and dried. The solution was treated with activated carbon, filtered through a pad of hydrous magnesium silicate and concentrated to an oil. This oil was dissolved in 50 ml of 10% ethyl acetate in dichloromethane and chromatographed on two columns in the same solvent. Refractive index was monitored at S 20, 250 ml/minute. The main peak in hold-back volumes 6-10 was cut into 1 liter portions which were separately evaporated. The first three of these all crystallized and the solids were recrystallized form isopropyl ether and hexane, giving 0.7 g of (S)2-(t-butoxycarbonyl)amino-4-methyl-(S)1-(2-thiazolyl)pentan-1-ol as crystals, mp 121°-122° C.

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