Common-intermediate strategy for synthesis of conduritols and inositols via beta-hydroxy cyclohexenylsilanes

Biological Properties of Cyclitols and Their Derivatives

Cyclitols are polyhydroxy cycloalkanes, each containing at least three hydroxyls attached to a different ring carbon atom. The most important cyclitol derivatives are inositols, quercitols, conduritols and pinitols, which form a group of naturally occurring polyhydric alcohols and are widely found in plants. In addition, synthetic production of cyclitols has gained importance in recent years. Cylitols are molecules synthesized in plants as a precaution against salt or water stress. They have important functions in cell functioning as they exhibit important properties such as membrane biogenesis, ion channel physiology, signal transduction, osmoregulation, phosphate storage, cell wall formation and antioxidant activity. The biological activities of these very important molecules, obtained both synthetically and from the extraction of plants, are described in this review.

Ring-fused cyclobutanes via cycloisomerization of alkylidenecyclopropane acylsilanes

A novel Lewis acid-catalyzed cycloisomerization of alkylidenecyclopropane acylsilanes is disclosed. The readily available starting materials participate in tandem Prins addition/ring expansion/1,2-silyl shift to grant access to bicyclo[4.2.0]octanes and bicyclo[3.2.0]heptanes, which are common motifs in terpenoid natural products. Notably, the transformation relies on the ability of acylsilanes to act sequentially as acceptors and donors on the same carbon atom.

A novel Lewis acid-catalyzed cycloisomerization of alkylidenecyclopropane acylsilanes is disclosed that involves tandem Prins addition/ring expansion/1,2-silyl shift to grant access to bicyclo[4.2.0]octanes and bicyclo[3.2.0]heptanes.

Concise synthesis of (+)-conduritol F and inositol analogues from naturally available (+)-proto-quercitol and their glucosidase inhibitory activity

An effective synthesis of (+)-conduritol F, (+)-chiro- and (+)-epi-inositols from naturally available (+)-proto-quercitol is described. This synthetic method provides a concise synthesis of cyclitols in enantiomerically pure form. Of the synthesized cyclitols, (+)-conduritol F potently inhibits type I α-glucosidase with an IC(50) value of 86.1 μM, which is five times greater than the standard antidiabetic drug, acarbose.

Enantioselective synthesis of (Z)-1,2-anti-2,5-anti-triol monosilyl ethers using a cross-metathesis allylboration sequence

The enantioselective synthesis of (Z)-1,2-anti-2,5-anti-triol monosilyl ethers via a two-step sequence involving olefin cross-metathesis of β-alkoxyallylboronate 4 and subsequent allylboration of the derived bisboryl intermediate 6 provides triol monoethers 7 with good to excellent diastereoselectivity.

A concise synthetic route to the conduritols from pentoses

A short synthetic strategy for preparation of the conduritols is described. The key step employs a zinc-mediated fragmentation of protected methyl 5-deoxy-5-iodo-d-pentofuranosides followed by an allylation of the intermediate aldehyde in the same pot. The allylation is performed with 3-bromopropenyl benzoate and occurs with good diastereoselectivity. An amino group can be introduced in the product by trapping the intermediate aldehyde as the imine prior to the allylation. The functionalised 1,7-octadienes, thus obtained, are converted into protected conduritols by ring-closing olefin metathesis.

Enantio- and diastereoselective synthesis of cyclic beta-hydroxy allylsilanes via sequential aldehyde gamma-silylallylboration and ring-closing metathesis reactions

[reaction: see text] Highly enantioenriched cyclic allylsilanes are prepared via stereoselective gamma-silylallylboration reactions of beta- or gamma-unsaturated aldehydes followed by ring-closing metathesis.