Silver(I) oxide assisted O-alkylation of 2,4-di-O-benzoyl-myo-inositol-1,3,5-orthoformate and its 6-O-substituted derivatives: Transannular participation of oxygen

The reaction of 2,4-di-O-benzoyl-myo-inositol-1,3,5-orthoformate and its 6-O-substituted derivatives with alkyl halides in the presence of silver (I) oxide has been studied systematically. The nature of the product obtained depends on the amount of silver (I) oxide and alkyl halides used as well as on the solvent employed for the reaction. By varying these parameters, the corresponding symmetrical 4,6-di-O-alkylated or 4-mono-O-alkylated myo-inositol-1,3,5-orthoformates can be obtained in good yields. These alkylations proceed by two different pathways which involve the transannular participation of the neighbouring oxygen. Results presented for the allylation of 2,4-di-O-benzoyl-myo-inositol-1,3,5-orthoformate suggest cleavage and allylation of the axial LC-benzoate moiety prior to allylation of the free C-6-hydroxyl group. Involvement of a myo-inositol orthoformate-silver complex during these alkylation reactions is suggested. (C) 1997 Elsevier Science Ltd.