Preparation of tetramethylcyclopropanecarboxylic-14C acid and insecticidal terallethrin-14C from it.

Esters of tetramethylcyclopropanecarboxylic acid (I) with (•})-allethrolonel1), (•}) -pyrethrolone2) and some others3) have activity comparable to that of corresponding esters of natural (+)-transchrysanthemic acid against some insect species. However, these esters show differences in toxicity to mammals which are probably resulted from differences in rates or pathways of metabolism. Therefore, radio-labelled compounds have been required to determine the metabolism of these tetramethylcyclopropanecarboxylates. Although Elliott, et al.4' reported the preparation of some esters labelled with tritium in the acid moiety, no method for 14C-labelling has been reported so far. This report describes a convenient method for the preparation of tetramethylcyclopropanecarboxylic-14C acid (I) and insecticidal terallethrin-14C (11) from it.