Via halogenolysis

Organobismuth(III) compounds with Bi-group 17 element bonds 

When the alkyl and aryl groups are both bound to the bismuth atom as mixed bismuthines, the alkyl ligand is replaced preferentially by halogen [85CB1031, 92BCJ3504]. 

Synthesis of (2-tert-butylsulfonylphenyl)iodo(4-methylphenyl)bismuthine S02 Bu 2 0 

To a well stirred suspension of [(2-fert-butylsulfonyl)phenyl]bis(4-methylphenyl)bismuthine (588 mg, 1 mmol) in diethyl ether (10 ml) was added dropwise a solution of iodine (254 mg, 1 mmol) in the same solvent (10 ml) under ambient conditions and until the starting material was completely consumed. The resulting pale yellow solution was concentrated under reduced pressure to leave an oily residue, which was recrystallized from methanol-benzene (5 1) to afford the iodobismuthine as pale yellow crystals (624 mg, 100%), m.p. 142-144°C [93JCS(P1)1169], 

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Scheme 1.19. Synthesis of alkyl and alkenyl halides via halogenolysis...

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