Reaktion #74825

Reaktionsgleichung

5-tert-butoxycarbonyl-4-methoxycarbonylmethyl-5-(2-pentynyl)-2-cyclopentenone

compound ( 2-a )

5-tert-butoxycarbonyl-4-methoxycarbonylmethyl-5-(2-pentynyl)-2-cyclopentenone

→

compound ( 2-b )

5-tert-butoxycarbonyl-4-methoxycarbonylmethyl-5-(cis-2-pentenyl)-2-cyclopentenone

Lösungsmittel

n-hexane

acetone

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigereduced at room temperature
2. 2
   FiltrationThe catalyst is filtered off from the reaction mixture
3. 3
   workup.DISTILLATIONthe solvent distilled off
4. 4
   SonstigeThe residue is purified by a silica gel column
5. 5
   workup.DISTILLATIONdistilled in a vacuum

Vorschrift

A 690 mg quantity of 5-tert-butoxycarbonyl-4-methoxycarbonylmethyl-5-(2-pentynyl)-2-cyclopentenone (compound (2-a)) is dissolved in a mixture of 5 ml of n-hexane and 5 ml of acetone and reduced at room temperature and atmospheric pressure with addition of 3.2 g of a Lindlar catalyst. The catalyst is filtered off from the reaction mixture, and the solvent distilled off. The residue is purified by a silica gel column and distilled in a vacuum, giving 5-tert-butoxycarbonyl-4-methoxycarbonylmethyl-5-(cis-2-pentenyl)-2-cyclopentenone (compound (2-b), R1 =t-Bu, R2 =CH3) in a yield of 99.8%, b.p. 81-84° C./0.005 mm Hg.

Quelle