yield of 70 compound 3 obtained previously 1 eq and the 3 chloro 1e tri n butylstannyl prop 1 ene 1 eq are dissolved in 2 ml eq of absolute ethanol containing a catalytic quantity of ki the mixture is shaken and heated to 70 u00b0 c for 16 hours after return to ambient temperature the mixture is treated with nahco 3 and extracted with ether the organic phase is washed in brine dried on na 2 so 4 and evaporated to give compound 5 each product is purified on a silica preparation plate using petroleum ether acoet 9 1 as elution phase to a solution containing 50 mg of compound 5 obtained at c 50 u03bcl of 0 1 n hcl and 50 u03bcl of 3 w v h 2 o 2 are added 5 u03bcl of na 125 i 37 mbq ml 1 mci ml the reaction is left at ambient temperature for 15 minutes then stopped with the addition of 100 u03bcl of a sodium bisulphite solution 300 mg ml the reaction medium is then made alkaline with a solution of nahco 3 500 mg ml and extracted with acoet 3 u00d7 1 ml the organic phase is evaporated.