Conformation inversion of an inositol derivative by use of silyl ethers: a modified route to 3,6-di-O-substituted-L-ido-tetrahydroxyazepane derivatives

The trans-diequatorial 3,4-diol of 2,5-di-O-benzyl-D-chiro-inositol cleaved selectively with the periodate ion in the presence of the trans-diaxial 1,6-diol to give a dialdehyde (dialdose) from which 3,6-di-O-benzyl-D-manno-tetrahydroxyazepane (1) was made. The trans-diaxial 1,6-diol of 3,4-di-O-allyl-2,5-di-O-benzyl-D-chiro-inositol was not cleaved satisfactorily by periodate, but replacement of the allyl substituents with tert-butyldimethylsilyl groups caused conformational inversion of the inositol ring, and the resulting trans-diequatorial 1,6-diol cleaved efficiently to give a dialdehyde from which 3,6-di-O-benzyl-L-ido-tetrahydroxyazepane (2) can be prepared.