1,3-Bis(phenylmercapto)propane and 1-chloro-3-(phenylmercapto)propane: useful precursors for 1,3-dilithiopropane synthons in the preparation of 1,5-diols

Treatment of 1,3-bis(phenylmercapto)propane (1) with an excess of lithium and a catalytic amount of DTBB (3.5 mol%) at −78°C followed by reaction with a carbonyl compound [tBuCHO, PhCHO, (PhCH2)2CO, Et2CO, (CH2)5CO, (CH2)7CO, (−)-menthone, Ph2CO] leads, after hydrolysis with water, to symmetrically substituted 1,5-diols (2). Starting from 1-chloro-3-(phenylmercapto)propane (3) and by successive treatment with: (a) lithium–naphthalene at −78°C; (b) a carbonyl compound {Me2CO, (CH2)5CO, (CH2)7CO, (−)-menthone, [CH3(CH2)4]2CO} at the same temperature; (c) lithium powder at −50°C; and (d) a second carbonyl compound [tBuCHO, PhCHO] at the same temperature and final hydrolysis with water yields unsymmetrically substituted 1,5-diols (4).