MULTIPLY METALLATED ORGANIC INTERMEDIATES: A TRIS(LITHIOMETHYL)CYCLOHEXANE AND A HEXALITHIOTRIMETHYLCYCLOHEXANETRIOLATE

Article abstract of DOI:10.1016/S0022-328X(00)99547-0

Lithium di-t-butylbiphenyl (LiDBB) readily cleaves alkyl-sulphur bonds to yield long-lived organolithiums.Using this reagent trilithio species (2b) was obtained from tris-phenylthioether (1b).The organometallic intermediates (2b) and (5b) were characterised by their reactions with electrophiles (e.g.D2O, CO2, Me3Si-OTf, Me-OTf) to yield di- and hexasubstituted cyclohexanes (3) and (6).Prolonged treatment of the trilithoxy tris-phenylthioether (1c) with excess LiDBB followed by addition of D2O and aqueous work-up gave a methyl-deuterated trimethylcyclohexanetriol (D_2.5-3aα) demonstrating that at least one penta- and hexalithio intermediate are involved.The structure of the latter intermediate could not be established unambiguously, but the unsymmetrical 1,1-dilithiated species (2) is prefered over the symmetrical hexalithio species (22) on the basis of extensive transmetallation observed at the tetra- or pentalithio stage (as seen in the deuterated phenylthiomethylcyclohexanetriol (15) and the absence of compelling evidence for the symmetrical tri(deuteriomethyl)cyclohexanetriol (3aβ), as judged from the CH3, CH2D, and CHD2 ratios in the deuterated product (D_2.5-3aα).