Reacción #216252

Ecuación de reacción

(R)-3-(t-butyl-dimethylsiloxy)tetradecanal

N-benzyl-N-phenylglycine methyl ester

potassium hydrogen sulphate

diisopropylamine

n-butyllithium

→

methyl (5R)-2-(N-benzylanilino)-5-(t-butyldimethylsiloxy)-3-hydroxyhexadecanoate

Rendimiento 7.9%

Disolventes

THF

THF

THF

hexane

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.ADDITIONwas added dropwise
2. 2
   workup.STIRRINGAfter stirring at -75° C. the reaction mixture
3. 3
   Extracciónextracted with ether
4. 4
   SecadoThe ether phase was dried
5. 5
   Concentraciónconcentrated
6. 6
   Otropartitioned between hexane and methanol/water (7:3)
7. 7
   Secadothe hexane phase was dried
8. 8
   Concentraciónconcentrated
9. 9
   Otrothe residue was chromatographed on silica gel with pentane/ether (5:1)

Procedimiento

A solution of 0.5 ml of diisopropylamine in 15 ml of THF was treated at 0° C. with 2.0 ml of a solution of 1.6M n-butyllithium in hexane and, after stirring, cooled to -75° C. Then, a solution of 765 mg of N-benzyl-N-phenylglycine methyl ester in 3 ml of THF was added. After stirring a solution of 700 mg of (R)-3-(t-butyl-dimethylsiloxy)tetradecanal (Example Bb)) in 5 ml of THF was added dropwise. After stirring at -75° C. the reaction mixture was poured into aqueous potassium hydrogen sulphate and extracted with ether. The ether phase was dried, concentrated, partitioned between hexane and methanol/water (7:3), the hexane phase was dried and concentrated and the residue was chromatographed on silica gel with pentane/ether (5:1). There were obtained 96.3 mg of methyl (5R)-2-(N-benzylanilino)-5-(t-butyldimethylsiloxy)-3-hydroxyhexadecanoate, diastereomer A, MS: 540 (M+ ·--C4H9 ·), and 142.8 mg of methyl (5R)-2-(N-benzylanilino)-5-(t-butyldimethylsiloxy)-3-hydroxyhexadecanoate, diastereomer B, MS: 540 (M+ ·--C4H9 ·), and 313.4 g of a mixture of the above two diastereomers.

Fuente