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)ClO(4) 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.
Fujioka
Hiromichi
H
Faculty of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565, Japan.
Kitagawa
Hidetoshi
H
Nagatomi
Yasushi
Y
Kita
Yasuyuki
Y