Synthese d'un Antagoniste Alpha Adrenergique Marque au Tritium: WB 4101 [benzodioxanyl-1,4-3H-2,3], ou N-[dimethoxy-2,6 phenoxyethyl] aminomethyl-2 benzodioxanne-1,4[3H-2,3]

The synthesis of an alpha adrenergic antagonist labelled with tritium: [(2,3-3H)-1,4-benzodioxanye] WB 4101 or 2-N[2,6 dimethoxyphenoxyethye] aminomethyl 2,3-3H-1,4 benzodioxan is described. 2-cyano-1,4-benzodioxan: 1 was prepared from catechol and 2-chloroacrylonitrille and then converted to 2-cyano-1,4-benzodioxin: 2 by the successive actions of N-bromosuccinimide in CCl4 and sodium iodide in acetone. 2 was reduced with lithium aluminium hydride into 2-aminomethyl-1,4-benzodioxin: 3 and then converted to 2-[N-(2,6-dimethoxyphenoxyethyl)-aminomethyl]-1,4-benzodioxin: 4a, and its hydrochloride: 4b. The catalytic reduction of 4a, 4b with tritium in various and in presence of various catalysts was studied. The best result was obtained with Wilkinson's catalyst in benzene giving rise to [(2,3-3H)1,4-benzodioxanyl]WB 4101 with a specific activity of 60 CilmMole. 3H.NMR and MS analyses are also described.