An improved method for 14C-labelling of farnesylacetic acid and its geranyl ester.

Abstract

Farnesylacetic acid was efficiently labelled with 14C at the 5-position and gefarnate, a potent ulcer inhibitor, was prepared from it in radioactive form for use in metabolic studies. Condensation of [carbonyl-14C]acetyl chloride (5) with t-butyl 2-ethoxymagnesiomalonate (6) followed by acid-catalyzed deprotection and decarboxylation gave ethyl 3-oxo[3-14C]butanoate (8). Alkylation of the keto ester (8) with geranyl bromide (9) afforded the unsaturated keto ester (10), which was hydrolyzed and decarboxylated to give geranyl[2-14C]acetone (11). Grignard reaction of 11 with cyclopropylmagnesium bromide followed by treatment with hydrobromic acid yielded [4-14C]homofarnesyl bromide (13). Cyanation of 13 with potassium cyanide and subsequent hydrolysis gave [5-14C]farnesylacetic acid (1) in 6.1% yield from barium [14C]carbonate (3). Chlorination of 1 followed by esterification with geraniol afforded [5-14C]gefarnate (2) in 88% yield.

• Authors: K Nishioka, I Nakatsuka, H Kanamaru
• Journal: Radioisotopes (Radioisotopes) Vol. 37 Issue 3 Pg. 133-9 (Mar 1988) ISSN: 0033-8303 [Print] Japan
• PMID: 3387600 (Publication Type: Journal Article)

Chemical References

• Carbon Radioisotopes
• Terpenes
• Gefarnate
• farnesylacetic acid
• Farnesol

Topics

• Carbon Radioisotopes
• Farnesol (analogs & derivatives)
• Gefarnate
• Isotope Labeling (methods)
• Terpenes