Method for preparing precursor of radioactive 3-iodobenzylguanidine

A method for preparing a precursor of radioactive 3-iodobenzylguanidine comprising the steps of:

• melting mixture of 3-iodobenzylamine hydrochloride and cyanamide, and then dissolving it in water, adding sodium bicarbonate so as to make 3-iodobenzylguanidine bicarbonate precipitate;
• using di-tert-butyl dicarbonate as a protecting agent for NH group and converting 3-iodobenzylguanidine bicarbonate into N,N′-bis(tert-butyloxycarbonyl)-N-(3-iodobenzyl) guanidine in dimethyl sulfoxide solution;
• and
• using palladium compounds as a catalyst of a substitution reaction between N,N′-bis(tert-butyloxycarbonyl)-N-(3-iodobenzyl)guanidine and bis(tri-n-butyltin) occurring in 1,4-dioxane and obtaining N,N′-bis(tert-butyloxycarbonyl)-3-(tri-n-butyltin)benzylguanidine (MSnBG) by the substitution reaction between N,N′-bis(tert-butyloxycarbonyl)-N-(3-iodobenzyl)guanidine and bis(tri-n-butyltin) occurring in 1,4-dioxane.