Successive treatment of bis (phenylthio) methane (1) with (a) n-butyllithium at 0° C,(b) a carbonyl compound [tBuCHO, Me2CO, Et2CO,(CH2) 5CO] at− 40° C,(c) lithium and a catalytic amount of DTBB (5%) and (d) a second carbonyl compound [iPrCHO, tBuCHO, Me2CO, Et2CO,(CH2) 5CO], both at− 78° C, leads, after hydrolysis, to the expected dihydroxy thioethers 5. When, after step (d), a second DTBB-catalysed lithiation is ...