2,6-Hepta-O-tert-butyldimethylsilyl α-cyclodextrin - A carbohydrate undecaol with all OH groups visible in NMR indicative of a partially disrupted hydrogen bond network.

During a synthesis of the well-known and useful building block 6-hexa-O-tert-butyldimethylsilyl α-cyclodextrin (2) by silylation of α-cyclodextrin (1) we isolated as a byproduct the oversilylated 2,6-hepta-O-tert-butyldimethylsilyl α-cyclodextrin (3) where one 2-OH group has also been silylated. This unsymmetrical new compound has a remarkable H NMR spectrum in CDCl where all 11 alcohol groups are visible. We have analyzed the spectrum of 3 using 1D and 2D 800 MHz NMR and are able to assign all the 11 alcohol protons.

New methods of modification of α-cyclodextrin.

While being some of the oldest supramolecular hosts, cyclodextrins remain very popular as molecular binders in materials, devices, artificial enzymes and more. The popularity is undoubtedly connected to the ready availability, carbohydrate biomass origin, biodegradability and water solubility of the cyclodextrins. Many of these applications require synthetic modification of the cyclodextrin - at the simplest the attachment of a linker - but also often attachment of several functional groups, lids, bridges .

Silylene acetals from cheap reagents: synthesis and regioselective opening.

In this communication, a practical method for using cheap and easily available silylene chlorides for diol protection is presented. The method is based on activation of the reagents using Finkelstein-like conditions. Silylene acetals of carbohydrates are synthesized, and it is furthermore shown how these can be regioselectively opened using Grignard reagents.

A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups.

An α-cyclodextrin protected with 2,4-dichlorobenzyl groups on the primary alcohols and ordinary benzyl groups on the secondary alcohols was prepared and subjected to DIBAL (diisobutylaluminum hydride)-promoted selective debenzylation. Debenzylation proceeded by first removing two dichlorobenzyl groups from the 6 positions and then removing one or two benzyl groups from the 3 positions.