A novel and efficient one-pot synthesis of tetrazole -derivatives such as Irbesartan and its analogues has been described from the primary acid amide derivatives. Thus 2-alkyl-3-[ P-( O-amidophenyl)benzyl]-1,3-diazaspiro[4.4]non-1-en-4-one derivatives or 4-[α-(acylamino)cyclopentamidomethyl]-2′-carboxamidobi-phenyl derivatives were treated with tributyltin chloride and sodium azide in O-xylene in the