MALONIC ESTER AND ACETOACETIC ESTER SYNTHESIS OF 2-[C-11,C-14]METHYL-FATTY ACIDS

Suitable conditions were sought for the synthesis of various 2-[C-11,C -14]methyl-fatty acids by malonic ester synthesis and acetoacetic eate r synthesis, both involving radio-methylation with [C-11,C-14]CH3I. Th e malonic eater synthesis gave 2-[C-11]methyl-fatty acids with over 60 % decay-corrected yields in about 40 min and the [C-14]products with s omewhat higher yields at a longer time. In the acetoacetic ester synth esis, several 2-[C-14]methyl-fatty acids were synthesized in 50-70% yi elds by the hydrolysis of the radio-methylated acetoacetates with a co ncentrated potassium hydroxide solution, together with by-product keto nes. This hydrolysis was completed in 5 min at 70 degrees C, whereas r ather drastic conditions or a longer time were needed for the thermal decarboxylation in the malonic eater synthesis. (C) 1997 Elsevier Scie nce Ltd.