THE ALLYL GROUP FOR PROTECTION IN CARBOHYDRATE-CHEMISTRY .26. THE PREPARATION OF INTERMEDIATES FOR THE SYNTHESIS OF 1D-MYO-INOSITOL 1,4,5-TRISPHOSPHATE, A 2ND MESSENGER FOR SIGNAL TRANSDUCTION IN CELLS

Racemic 1,2,4-tri-O-benzyl-5,6-0-isopropylidene-myo-inositol was prepared by a new route involving crotyl (but-2-enyl) ethers and converted into the (-)-omega-camphanates to give the pure crystalline 1L-diastereoisomer and the chirally impure, syrupy ID-diastereoisomer. The latter was converted via the 1-0-allyl or 1-0-p-methoxybenzyl ethers into chirally pure ID-2,3,6-tri-O-benzyl-myo-inositol [required as an intermediate for the synthesis of ID-myo-inositol 1,4,5-trisphosphate (1,4,5-IP3)], which was also prepared by de-p-methoxybenzylation of ID-2,3,6-tri-O-benzyl-1,5-di-0-p-methoxybenzyl-myo-inositol. Racemic 2,4-di-O-benzyl-5,6-0-isopropylidene-1-0-p-methoxybenzyl-myo-inositol was prepared in a similar way to the analogous tribenzyl ether (using crotyl ethers) and the omega-camphanate esters behaved similarly, allowing efficient resolution by crystallisation of the (-)- and (+)-omega-camphanates. Racemic 1,2,4-tri-O-allyl-3-0-(but-2-enyl)-myo-inositol was resolved via the (-)-omega-camphanates and was also converted into 1,2,4-tri-O-(CiS-prop-1-enyl)-myo-inositol, an alternative intermediate for the synthesis of 1,4,5-IP3.