反应 #554668

反应方程式

methyl cyanoformate

lithium diisopropylamide

4-benzyl-3-methyl-1,4-oxazepan-5-one

HMPA

→

methyl 4-benzyl-3-methyl-5-oxo-1,4-oxazepane-6-carboxylate

溶剂

THF

THF

反应条件

后处理

1. 1
   workup.STIRRINGstirred for 20 min
2. 2
   其他partitioned between saturated aqueous ammonium chloride solution and ethyl acetate (2×150 mL)
3. 3
   干燥The combined organic layers were dried over sodium sulfate
4. 4
   浓缩concentrated
5. 5
   其他The residue was purified by flash column chromatography (20% EtOAc in hexanes initially

实验过程

A solution of lithium diisopropylamide in THF (0.101 M, 100 mL, 10.1 mmol, 1.30 equiv) freshly prepared at −78° C. was added via cannula to a solution of 4-benzyl-3-methyl-1,4-oxazepan-5-one (4-3, 1.71 g, 7.80 mmol, 1 equiv) in THF (100 mL) at −78° C. and the resulting mixture was stirred for 20 min. HMPA (1.36 mL, 7.80 mmol, 1.00 equiv) was added followed by methyl cyanoformate (1.24 mL, 15.6 mmol, 2.00 equiv). The resulting mixture was warmed to 0° C., stirred for 20 min, and then partitioned between saturated aqueous ammonium chloride solution and ethyl acetate (2×150 mL). The combined organic layers were dried over sodium sulfate and concentrated. The residue was purified by flash column chromatography (20% EtOAc in hexanes initially, grading to 100% EtOAc) to give methyl 4-benzyl-3-methyl-5-oxo-1,4-oxazepane-6-carboxylate (4-4) as a mixture of diastereomers (colorless oil). LRMS m/z (M+H) 278.2 found, 278.1 required.

来源