Reaction #44022

Reaction equation

Ethyl 1-(4-chlorophenylsulfonyl)-6-ethyl-4-oxopiperidine-2-carboxylate

ethyl 1-(4-chlorophenylsulfonyl)-6-ethyl-4-oxopiperidine-2-carboxylate

TMSCl

ethylene glycol

→

mixture

Yield 96.0%

ethyl 8-(4-chlorophenylsulfonyl)-9-ethyl-1,4-dioxa-8-azaspiro[4.5]decane-7-carboxylate

Yield 96.0%

Solvents

CH2Cl2

Conditions

Workup

1. 1
   Temperaturerefluxed under nitrogen for 3 hours
2. 2
   ConcentrationThe reaction mixture was concentrated tinder reduced pressure
3. 3
   WashThe aqueous layer was washed with several more portions of EtOAc
4. 4
   Dryingdried over Na2SO4
5. 5
   Concentrationconcentrated

Procedure

Ethyl 1-(4-chlorophenylsulfonyl)-6-ethyl-4-oxopiperidine-2-carboxylate (109; 5.31 g, 14.2 mmol), TMSCl (5.41 ml, 42.6 mmol), and ethylene glycol (3.96 ml, 71.0 mmol) were added to CH2Cl2 (50 ml) and refluxed under nitrogen for 3 hours. The reaction mixture was concentrated tinder reduced pressure, and taken up in equal portions of EtOAc and water. The aqueous layer was washed with several more portions of EtOAc, dried over Na2SO4, and concentrated to give 5.67 g (96%) of a mixture of cis/trans (4:96) isomers as a clear oil which solidified upon standing. The material was used without further purification.

Source