The stereochemistry of cyclic derivatives of carbohydrates

p-Toluenesulfonic acid adorned on MCM-41: an efficient and mild catalyst for the regio/chemo-selective hydrolysis of terminal isopropylidene acetals

Regio/chemo-selective hydrolysis of a 5,6-O-isopropylidene group over a 1,2-O-isopropylidene group is accomplished to obtain corresponding diols in good to excellent yields within 4-5 hours using the p-toluenesulfonic acid impregnated MCM-41 (PTSA-MCM-41) catalyst in acetonitrile and water (9:1, v/v) at room temperature. Other sensitive hydroxyl protecting groups such as naphthyl, toluoyl, pivaloyl, benzoyl, and benzyl are compatible with this methodology. The low cost of the PTSA-MCM-41 catalyst and ease of separation of product from the reaction mixture are significant advantages of this method, which makes it useful in the multigram scale operation.

High-performance liquid chromatographic analysis of dianhydrogalactitol in plasma by derivatization with sodium diethyldithiocarbamate

A high-performance liquid chromatographic method is described for measuring submicrogram quantities of dianhydrogalactitol, a promising anti-neoplastic agent, in plasma. The drug is derivatized directly in plasma with sodium diethyldithiocarbamate to form a bis(dithiocarbamoyl) ester which absorbs UV light at 254 nm (am 17,000). The derivatized product is then extracted quantitatively into chloroform and separated by normal phase chromatography (muBondpak CN column). Dianhydrogalactitol concentration below 50 ng/ml of plasma can be detected in the eluent.

Conformations of the Pyranoid Sugars. I. Classification of Conformers

An improved system is presented for indicating the principal conformations of pyranoid sugars and derivatives, by attaching two symbols to the systematic name. The first symbol shows the kind of pyranoid ring; for example, B = a boat, C = the chair, and S = a skew form. (The three boat and six skew rings are distinguished by subscript numerals referring to exoplanar ring-atoms.) The second symbol differentiates between two conformations that have the same type of ring, by describing as A or E the axial or equatorial character of the reference group at a selected ring-atom. If the anomeric group is not quasi, the α anomeric group is used as the reference group. For sugars and derivatives having a quasi anomeric group, and for relatives lacking an anomeric group, the A or E classification is based on the reference group at the lowest numbered, nonquasi, asymmetric ring-atom.