Keeping the balance with electron-withdrawing groups! The unusual form of a phosphinous acid can be stabilized with respect to the corresponding
phosphane oxide tautomer by the influence of electron-withdrawing groups. In their Full Paper
, B. Hoge et al. describe an efficient strategy
for the synthesis of phosphinous acids and phosphane oxides featuring one pentafluoroethyl group with an additional trifluoromethyl,
pentafluorophenyl, or phenyl substituent. The differing stabilization of the phosphinous acid form is evidenced in the tautomeric equilibrium.