The pyrethrins and related compounds. XVII. Preparation of the insecticide bioresmethrin (5-benzyl-3-furylmethyl (+)-trans-chrysanthemate) and related compounds labelled with deuterium or tritium on the furan ring

2-²H-5-Benzyl-3-furylmethyl esters exclusively are obtained from an exchange reaction of the parent esters with deuterium oxide and a trace of acid (n.m.r. and mass spectrometric control). Similarly, with tritiated water, 6 insecticidal esters of 5-benzyl-3-furylmethyl alcohol give the corresponding [2-³H]esters, each with specific activity of approx. 500 mCi/mmol.