Orthogonally Protected Cyclohexanehexols by a “One Reaction – One Product” Approach: Efficient Access to Cyclitols and Their Analogs

Abstract

Differentially protected myo-inositol derivatives were prepared from commercially available myo-inositol through regioselective O-alkylation reactions, which give a single product in each step. These derivatives were converted into six isomeric inositol derivatives carrying orthogonal hydroxy protecting groups. For all these reactions, conditions were chosen to prevent the formation of isomeric products, which

Synthesis of Amino Core Compounds of Galactosyl Phytosyl Ceramide Analogs for Developing iNKT-Cell Inducers

“…A trace amount of acid generated during the chromatography might weaken the ether protecting group [49]. On the other hand, the intramolecular SN 2 reaction mediated by a suitable stereochemistry has been addressed [50]. In the present case, the nucleophilicity of the OBn group might be displayed by orienting itself through a conformational change of the backbone as evidenced from the 1 H-NMR in the preparations.…”

Useful access to enantiomerically pure protected inositols from carbohydrates: the aldohexos-5-uloses route

“…Although some attractive findings have been reported so far [46–47], the regioselective protection of inositols is still a troublesome area due to the comparable reactivity of the secondary hydroxy functions. Therefore, the carbocyclization of a selectively protected dicarbonyl sugar, namely the L- lyxo derivative 20 , whose synthesis will be presented in a forthcoming paper, has been investigated (Scheme 2).…”

myo-Inositol 1,3-acetals as early intermediates during the synthesis of cyclitol derivatives

“…However, regioselectivity of the reductive cleavage of myo-inositol orthoesters carrying unsymmet- rical substituents could not be ascertained clearly. 45,57 Reduction of the un-symmetrically O-substituted orthoformate racemic 30 gave the C5-alcohol 48 as a single isolated product 58 while, reduction of the orthobenzoate moiety in 36 resulted in the formation of a mixture of products from which the benzylidene acetal 54 was isolated in 60% yield. 45 Reduction of 36 with an excess of DIBAL-H gave a mixture of isomeric diols 60 and 61, 45 but this result is not sufficient to conclude the sole intermediacy of the 1,3-acetal 63 (Scheme 7).…”

“…45,57 Reduction of the un-symmetrically O-substituted orthoformate racemic 30 gave the C5-alcohol 48 as a single isolated product 58 while, reduction of the orthobenzoate moiety in 36 resulted in the formation of a mixture of products from which the benzylidene acetal 54 was isolated in 60% yield. 45 Reduction of 36 with an excess of DIBAL-H gave a mixture of isomeric diols 60 and 61, 45 but this result is not sufficient to conclude the sole intermediacy of the 1,3-acetal 63 (Scheme 7). This is because no data on the regioselectivity of the reductive cleavage of 1,3-acetals or the relative ease of reduction of the myo-inositol 1,3-and 1,5-acetals are available.…”

“…[37][38][39][40][41][42] Due to the strong intramolecular hydrogen bonding between the C4-and C6-hydroxyl groups of myo-inositol orthoesters, and differences in the ability of the hydroxyl groups (of [18][19][20][21][22] to form chelates with metal ions, reaction of the hydroxyl groups of these orthoesters with alkyl halides can be controlled to obtain mono-, di-or, triethers exclusively (Scheme 3). [43][44][45] Hence a variety of orthogonally protected myo-inositol derivatives can be obtained in a short time. Reductive cleavage of these orthoesters results in the formation of 1,3 acetals (consequently releasing one of the three hydroxyl groups of the orthoester moiety), which are fast becoming early intermediates for phosphoinositol synthesis.…”