The lithiation of thianthrene 1 with lithium and a catalytic amount of 4,4'-di-tert-butylbiphenyl (DTBB, 4% molar) in THF at -90 o C, followed by reaction with a carbonyl compound [Bu t CHO, Me 2 CO, Et 2 CO, (CH 2 ) 5 CO] at the same temperature, gives an intermediate, which was lithitated again and reacted with a second carbonyl compound [Bu t CHO, PhCHO, Ph(CH 2 ) 2 CHO, Me 2 CO, Et 2 CO, (CH 2 ) 5 CO] to give, after the final hydrolysis, the expected diols 2. Compounds 2 are easily cyclised under acidic conditions (85% H 3 PO 4 ) to yield the expected phthalans in almost quantitative yields. Finally, when after the reaction with the first carbonyl compound (PhCHO, Me 2 CO), carbon dioxide was used as the second electrophile, the expected substituted phthalides 3 were obtained after acidic work-up.