115015-97-9

An efficient method for the resolution of myo-inositol 1,3,5-orthoformate has been developed. The triol, 1 was converted to diastereomers via reaction with (S)-O-acetylmandeloyl chloride. Conditions were optimized for a diastereomeric ratio of 7:3. Both t

Racemic 4-O-allyl-myo-inositol-1,3,5-orthoest-ers were resolved as the corresponding diastereomeric dicamphanates by crystallization from alcoholic solvents. Crystals of the two diastereomers of myo-inositol orthoacetate and one diastereomer each of myo-inositol orthoformate and myo-inositol orthobenzoate were obtained in >99% purity, on gram scale. The configuration of all these diastereomers was established by conversion to known chiral myo-inositol derivatives as well as by single crystal structure analysis. It is interesting to note that the procedures for the separation of diastereomeric myo-inositol orthoesters could be evolved due to the knowledge of crystal growth and crystal structures of inositol derivatives of comparable molecular structures. Due to the synthetic versatility of myo-inositol orthoesters, the methods described provide rapid and convenient access to a variety of chiral inositol derivatives with high synthetic potential.

Chiral desymmetrisation of myo-inositol 1,3,5-orthobenzoate via the formation of diastereoisomeric bis[(1S)-(-)-camphanate] esters provides a convenient and fast route to precursors for biologically important inositol phosphates and lipids, and to synthet

Alkylation of racemic 2,4-di-O-acyl-6-O-sulfonyl-myo-inositol 1,3,5-orthoformates mediated by silver(I) oxide affords the corresponding racemic 2,4-di-O-alkyl-6-O-sulfonyl-myo-inositol 1,3,5-orthoformates in good yields. Control experiments suggest that these unusual reactions are due to intramolecular assistance by the sulfonyl group. O-Alkylation reactions of myo-inositol 1,3,5-orthoformate derivatives provide a new route for the synthesis of important ether derivatives of myo-inositol, which are intermediates for the preparation of phosphoinositols. The utility of this method is demonstrated by the preparation of D- and L-2,4-di-O-benzyl-myo-inositols, which were obtained by benzylation of 2,4-di-O-benzoyl-6-O-camphorsulfonyl-myo-inositol 1,3,5-orthoformate and 2,6-di-O-benzoyl-4-O-camphorsulfonyl-myo-inositol 1,3,5-orthoformate. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.

The regioselectivity of sulfonylation of myo-inositol orthoesters was controlled by the use of different bases to obtain the desired sulfonate. Monosulfonylation of myo-inositol orthoesters in the presence of one equivalent of sodium hydride or triethylamine resulted in the sulfonylation of the 4-hydroxyl group. The use of pyridine as a base for the same reaction resulted in sulfonylation of the 2-hydroxyl group. Disulfonylation of these orthoesters in the presence of excess sodium hydride yielded the 4,6-di-O-sulfonylated orthoesters. However, the use of triethylamine or pyridine instead of sodium hydride yielded the 2,4-di-O-sulfonylated orthoester. Sulfonylated derivatives of myo-inositol orthoesters were stable to conditions of O-alkylation but were cleaved using magnesium/methanol or sodium methoxide in methanol to regenerate the corresponding myo-inositol orthoester derivative. These new methods of protection-deprotection have been used: (i) for the efficient synthesis of enantiomers of 2,4-di-O-benzyl-myo-inositol, which are precursors for the synthesis of D- and L-myo-inositol 1,3,4,5-tetrakisphosphate; (ii) for the preparation of 2-O-benzyl-myo-inositol which is a precursor for the preparation of myo-inositol 1,3,4,5,6-pentakisphosphate.

Sulfonylation of myo-inositol 1,3,5-orthoesters with alkyl or aryl sulfonyl chlorides in the presence of sodium hydride gives the corresponding 4,6-di-O-sulfonates in good yields. These sulfonates can be cleaved with magnesium in methanol to generate the free myo-inositol derivative. This methodology was used for the preparation of racemic 2,4-di-O-benzyl-myo-inositol and 2-O-benzyl-myo-inositol, which are precursors for some phosphoinositols.

D-Ins(1,3,4,5)P4 and unnatural L-Ins(1,3,4,5)P4 were prepared in gram-quantities from D- and L-2,6-di-O-benzyl-myo-inositol by a chemical phosphorylation and deprotection step in high yield and purity without extensive purification.

Details of the products obtained by the tin-mediated allylation and benzylation of 1,2-O-isopropylidene-myo-inositol, which were previously described in a preliminary communication, are provided here. Some of the products from these reactions, particularl

1,3,4,6-Tetra-O-allyl-myo-inositol was converted into the 2,5-di-O-benzyl- and 2,5-di-O-p-methoxybenzyl ethers, and the products were deallylated to give the 2,5-di-O-benzyl (and p-methoxybenzyl) ethers of myo-inositol, which were converted into the mono-

The 1,4,5-tris-, 1,3,4-tris-, and 1,3,4,5-tetrakis-phosphates of 1D-myo-inositol have been prepared in their enantiomerically pure forms from the two enantiomers of 1,2:5,6-di-O-cyclohexylidene-myo-inositol. A facile enzymic preparation is also described

Multigram quantities of the title compounds in their enantiomerically-pure forms have been prepared by employing a chiral precursor which can be obtained via a facile enzymatic process.

An L- or D-tartaric acid monoester is shown to be an excellent chiral auxiliary for asymmetric esterification of myo-inositol derivatives and one of the resultant esters with high optical purity is utilized for a short-step and practival synthesis of D-my

-

Novel selective alkylations of myo-inositol orthoformate (4) have been used to prepare a series of protected myo-inositol derivatives, (5a-e), (7), (10), (12), and (16).These intermediates have been used in efficient total syntheses of myo-inositol 2-phosphate, (9); myo-inositol 4-phosphate, (6); myo-inositol 1,3-bisphosphate, (18); and myo-inositol 1,3,4,5-tetrakisphosphate (14).This report represents the first total synthesis of the important natural metabolites (14) and (18) and significantly improved methods of preparation of (6) and (9).

A convenient approach to the preparation of the title compounds illustrating selective protection, optical resolution and phosphorylation is presented.

-

-

-

-