Reaction #674298

Reaction equation

potassium t-butoxide

tert-butyl 4-oxopiperidine-1-carboxylate

hexane

→

tert-butyl 4-methylenepiperidine-1-carboxylate

Yield 94.2%

Solvents

ether

ether

Conditions

Workup

1. 1
   Temperatureat reflux for 2 hrs
2. 2
   Temperatureto warm to room temperature
3. 3
   workup.STIRRINGstirred at room temperature for 1 h
4. 4
   workup.STIRRINGThe mixture was then stirred
5. 5
   Temperatureat reflux overnight (16 h)
6. 6
   TemperatureThe mixture was cooled to room temperature
7. 7
   workup.STIRRINGThe mixture was stirred for 10 min
8. 8
   Filtrationfiltered
9. 9
   Washeluted with Hexane/EtOAc (100/100 mL)
10. 10
    ConcentrationThe combined organic solution was concentrated
11. 11
    Otherto give the residue which
12. 12
    Otherwas purified by CombiFlash (100 g silica gel column, EtOAc/Hex=0-30%)

Procedure

To a suspension of methyltriphenylphosphonium bromide (36.3 g, 101.6 mmol, 1.35 equiv) in ether (dry, 300 mL) was added potassium t-butoxide (11 g, 98 mmol, 1.3 equiv) in one portion at 0° C. under nitrogen balloon. The mixture was then stirred at reflux for 2 hrs. The hot reaction mixture was cooled to 0° C. with an external ice-bath and then a solution of tert-butyl 4-oxopiperidine-1-carboxylate (15 g, 75.3 mmol, 1.0 equiv) in ether (60 mL) was added dropwise. The mixture was allowed to warm to room temperature and stirred at room temperature for 1 h. The mixture was then stirred at reflux overnight (16 h). The mixture was cooled to room temperature and hexane (300 mL) was added. The mixture was stirred for 10 min, filtered and eluted with Hexane/EtOAc (100/100 mL). The combined organic solution was concentrated to give the residue which was purified by CombiFlash (100 g silica gel column, EtOAc/Hex=0-30%) to afford 14 g (yield 94%) of tert-butyl 4-methylenepiperidine-1-carboxylate as a colorless oil.

Source