A synthesis of 10-and 1L-myo-inositol 1,3,4,5-tetraphosphate ( l a and l b resp.) is described. The dibenzylated myo-inositols 9a and 9b, which, by phosphorylation, gave l a and lb, respectively, were prepared via two routes. On the one hand, the racemate 3a/3b, obtained from myo-inositol, was resolved by its transformation into the diastereoisomeric carbamates 5a and 5b. Benzylation and deprotection of 5a and 5b gave the enantiomers 9a and 9b, respectively. On the other hand, treatment of the diester 18 with pig h e r esteruse gave the ester Zla with high enantiomeric excess. Benzylation and deprotection of Zla yielded 9b. The dibenzyl derivative 9a was obtained using the same enzymatic hydrolysis followed by a protection-deprotection sequence.Introduction. -myo-Inositol 1,4,5-triphosphate (IP,) plays an important role as a cellular second messenger [ 11. IP, is produced by the hydrolysis of phosphatidylinositol 4,5-diphosphate and it controls the liberation of Caz+ from an intracellular store. The investigations of the mechanism of these two processes showed the role of other inositol phosphates [2] and among them of myo-inositol 1,3,4,5-tetraphosphate (IP,) [3]. This phosphate appears to also be a second messenger and to be formed from IP, [4]. To the best of our knowledge, the absolute configuration of the biologically active IP, l a has been proved by correlation with b m y o -inositol 1,4,5-triphosphate,
