[en] An efficient synthesis of the analytically useful title compound 2c (1,1,3,3-(²H₄)-4-hydroxydebrisoquine sulphate), utilising a two-step deuteration(¹H/²H exchange of 3-nitromethylphthalide,4, and LiAl²H₄ reduction of 3,3-(²H ₂)-4-hydroxy-1,2,3,4-tetrahydroisoquinolin-1-one, 6), is described. (author)