Isobutylene → tert-Butyl (R)-2-piperidinecarboxylate

Participants

Reaction Steps

tert-Butyl (2R)-1-[(1,4-dichloro-7-isoquinolinyl)sulphonyl]-2-piperidinecarboxylate ##STR195## Concentrated H2SO4 (2.0 ml) was added to an ice-cold solution of 2 -(R)-piperidine carboxylic acid (415 mg, 3.21 mmol) in dioxan (10 ml). Condensed isobutylene (40 ml) was carefully added, and the reaction stirred at room temperature in a sealed vessel for 21 h. The reaction mixture was poured into an ice-cooled solution of Et2O (100 ml) and SN NaOH (20 ml), the mixture allowed to warm to room temperature with stirring, and then diluted with water. The phases were separated, the organic layer washed with 1N NaOH, then concentrated in vacuo, to half the volume, and extracted with 2N HCl. The combined acidic extracts were basified using 1N NaOH, and extracted with CH2Cl2, the combined organic solutions dried (MgSO4) and evaporated in vacuo to afford tert-butyl 2(R)-piperidine carboxylate (210 mg, 1.4 mmol) as an oil.

Provenance & Evidence