Revisiting the amination of organozincs with benzenediazonium tetrafluoroborate

Triarylzincates prepared by transmetallation of corresponding Grignard reagents react with benzenediazonium tetrafluoroborate with a 1:1.1 molar ratio of Grignard reagent: aminating reagent in THF at -15degreesC for one hour to give arylpheny1diazenes in high yields. Arylphenyldiazenes are easily reduced to arylamines using NaBH4/NiCl2.6H(2)O. Alkyl and benzylzinc reagents were observed not to react with benzenediazonium tetrafluoroborate in the experimental conditions. Transmetallation of Grignard reagents to arylzinc chlorides and triarylzincates can also be carried out in the presence of benzenediazonium tetrafluoroborate and in situ prepared organozincs can be also aminated effectively at -15degreesC in three hours, however preprepared triarylzincates are the most effective reagents. Benzenediazonium tetrafluoroborate can be easily prepared and its reaction with arylzincs provides a new and convenient route for electrophilic amination of organozincs.