Asymmetric induction via an intramolecular haloetherification reaction of chiral ene acetals: A novel approach to optically active 1,4- and 1,5-diols

An asymmetric synthesis of chiral 1,4- and 1,5-diols has been developed from the ene acetals 1a and 1c, prepared from the corresponding aldehydes and chiral C-2-symmetric diols, involving remote asymmetric induction as a key step. In the first step, treatment of 1 with I(coll)(2)ClO4 in the presence of an alcohol afforded the macrocyclic acetals (3-5 and 7) in a highly stereoselective manner. Subsequent nucleophilic substitution of iodide followed by a Grignard reaction with complete retention of stereochemistry and a final deprotection of the diphenylethylene or diphenylpropylene unit successfully gave optically active 1,4- and 1,5-diols in good yields.