Reaktion #74826

Reaktionsgleichung

5-methoxycarbonyl-4-methoxycarbonylmethyl-5-(2-pentynyl)-2-cyclopentenone

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

compound ( 2-a )

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

Hydrogen

→

compound ( 2-b )

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

Lösungsmittel

acetone

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONis added to the solution
2. 2
   Sonstigehas absorbed the theoretical amount of the gas
3. 3
   SonstigeOn completion of the reaction
4. 4
   Filtrationthe catalyst is filtered off from the reaction mixture
5. 5
   Einengenthe filtrate is concentrated at reduced pressure
6. 6
   workup.DISTILLATIONThe residue is distilled in a vacuum

Vorschrift

A 4.5 g quantity of 5-methoxycarbonyl-4-methoxycarbonylmethyl-5-(2-pentynyl)-2-cyclopentenone (compound (2-a)) is dissolved in a mixture of 50 ml of n-hexhane and 50 ml of acetone, and 7 g of a Lindlar catalyst is added to the solution. Hydrogen gas is introduced into the solution with stirring. The reaction is completed when the solution has absorbed the theoretical amount of the gas. On completion of the reaction, the catalyst is filtered off from the reaction mixture, and the filtrate is concentrated at reduced pressure. The residue is distilled in a vacuum, affording 5-methoxycarbonyl-4-methoxycarbonylmethyl-5-(cis-2-pentenyl)-2-cyclopentenone (compound (2-b), R1 =CH3, R2 =CH3) in a yield of 99.8%, b.p. 81-85° C./0.005 mm Hg.

Quelle