Reaction #985304

Reaction equation

Propargylaldehyde diethylacetal

N-methoxy-N-methylacetamide

n-butyllithium

hexane

→

colorless oil

Yield 72.5%

5,5-Diethoxy-pent-3-yn-2-one

Yield 72.5%

Solvents

THF

THF

Conditions

Workup

1. 1
   workup.WAITAfter 30 min at −30° C.
2. 2
   Otherthe reaction was quenched by addition of saturated NH4Cl solution (20 mL)
3. 3
   ExtractionThe product was extracted with AcOEt (2×200 mL), saturated solution of NH4Cl (2×200 mL)
4. 4
   Otherdried
5. 5
   Concentrationconcentrated

Procedure

Propargylaldehyde diethylacetal (40 g, 312 mmol) was dissolved in THF (200 mL) under argon and cooled to −70° C. Then a 1.6 M solution of n-butyllithium in hexane (234 mL, 374 mmol) was added and stirring continued for 30 min at −30° C. Then N-methoxy-N-methylacetamide (38.6 g, 374 mmol) in THF (10 mL) was added. After 30 min at −30° C., the reaction was quenched by addition of saturated NH4Cl solution (20 mL). The product was extracted with AcOEt (2×200 mL), saturated solution of NH4Cl (2×200 mL), dried and concentrated. Chromatography on silica gel with a heptane/ethyl acetate gradient 100:0 to 95:5 gave 38.5 g (72%) of a colorless oil. GC/MS: m/z=232(M).

Source