Synthesis and Evaluation of New 1,7-Dioxaspiro[5.5]undecane Ligands: Implications for the Use of Diols in the Desymmetrization of meso Epoxides

The synthesis and preliminary evaluation of two new chiral 1,7-dioxaspiro[5.5]undecane ligands is described. The compounds of interest are readily available in enantiomerically pure form. Chiral organotitanium complexes prepared from these ligands catalyze the ring opening reaction of meso epoxides by TMSN3. A key observation suggests that silylation of the ligand competes with catalyst turnover in this application. Implications for the use of diol ligands are discussed.