The reaction of t-butylphenyl sulfone (Ia) with n-butyllithium at −20 to −30° in THF-ether leads to lithium (21-t-butyl-61-lithium-biphenyl)sulfinate (VI). On hydrolysis 21-t-butylbiphenyl-2- sulfinic acid (VII) was obtained whereas carboxylation led to 61-carboxy-21-t-butylbiphenyl-2-sulfinic acid (VIIIa). The structures were confirmed by physical methods as well as by hydrodesulfurization and by