Solvent effects in the fluorination of aromatic molecules with ‘F-TEDA-BF4’
摘要:
The type of functionalization of an aromatic molecule achieved with 1-chloromethyl-4-fluoro-1,4-diazobicyclo-(2,2,2)octane bis-tetrafluoroborate, 'F-TEDA-BF4', in trifluoroacetic acid depends on its structure: naphthalene and phenanthrene gave fluorinated products, anthracene gave the trifluoroacetate, while an addition process occurred with 9-methoxy-phenanthrene in methanol, and an addition-elimination process in trifluoroacetic acid.
The photolysis of 10,10-difluorophenanthren-9(10H)-one 1 in different solvents shows that the major competing reaction of the diradical formed by α-cleavage: recombination and hydrogen atom abstraction depends on the hydrogen atom donating ability of the solvent. Photolysis of 1 in cyclohexane in the presence of air or oxygen leads mainly to α-cleavage while photoreduction with the formation of 10