[I:1]I.[CH2:3]([N:10]1[CH2:18][C:17]2([C:19]([O:21][CH3:22])=[O:20])[CH:12]([C:13](=NN)[CH2:14][CH2:15][CH:16]2[C:23]2[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=2)[CH2:11]1)[C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1.O.C(OCC)(=O)C>O1CCCC1.C(N(CC)CC)C>[CH2:3]([N:10]1[CH2:18][C:17]2([C:19]([O:21][CH3:22])=[O:20])[CH:12]([C:13]([I:1])=[CH:14][CH2:15][CH:16]2[C:23]2[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=2)[CH2:11]1)[C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=152.07 g of iodine, in solution in 250 cm3 of tetrahydrofuran, were added dropwise to a solution of 37.75 g of methyl (3aRS,4SR,7aRS)-2-benzyl-7-hydrazono-4-phenyloctahydroisoindole-3a-carboxylate in 200 cm3 of tetrahydrofuran and 43 cm3 of triethylamine. Stirring was maintained at room temperature for one hour after the end of the addition. 1 dm3 of water and 1 dm3 of ethyl acetate were then added. The organic phase was separated by settling, washed successively with a saturated sodium hydrosulphite solution and then with a saturated sodium chloride solution, and dried over magnesium sulphate. After concentrating the solvent under reduced pressure, the residue was purified by flash chromatography on silica gel (230-400 mesh), elution being carried out with a mixture of cyclohexane and of ethyl acetate (95/5 by volume). 22.25 g (47%) of methyl (3aRS,4SR,7aRS)-2-benzyl-7-iodo-4-phenyl-2,3,3a,4,5,7a-hexahydro-1H-isoindole-3a-carboxylate were thus obtained in the form of a yellow pasty solid, the characteristics of which were as follows:
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