l-Fucose from Vitamin C with Only Acetonide Protection

Synthesis and Structural Characteristics of all Mono- and Difluorinated 4,6-Dideoxy-d-xylo-hexopyranoses

Protein-carbohydrate interactions are implicated in many biochemical/biological processes that are fundamental to life and to human health. Fluorinated carbohydrate analogues play an important role in the study of these interactions and find application as probes in chemical biology and as drugs/diagnostics in medicine. The availability and/or efficient synthesis of a wide variety of fluorinated carbohydrates is thus of great interest. Here, we report a detailed study on the synthesis of monosaccharides in which the hydroxy groups at their 4- and 6-positions are replaced by all possible mono- and difluorinated motifs. Minimization of protecting group use was a key aim. It was found that introducing electronegative substituents, either as protecting groups or as deoxygenation intermediates, was generally beneficial for increasing deoxyfluorination yields. A detailed structural study of this set of analogues demonstrated that dideoxygenation/fluorination at the 4,6-positions caused very little distortion both in the solid state and in aqueous solution. Unexpected trends in α/β anomeric ratios were identified. Increasing fluorine content always increased the α/β ratio, with very little difference between regio- or stereoisomers, except when 4,6-difluorinated.

Crystal structure of 6-azido-6-de-oxy-1,2-O-iso-propyl-idene-α-d-gluco-furan-ose

Short syntheses to high Fsp³ index natural-product analogues such as imino­sugars are of paramount importance in the investigation of their biological activities and reducing the use of protecting groups is an advantageous synthetic strategy. In this case only an iso­propyl­idene group was employed towards the synthesis of seven-membered ring imino­sugars.

Short syntheses to high Fsp³ index natural-product analogues such as imino­sugars are of paramount importance in the investigation of their biological activities and reducing the use of protecting groups is an advantageous synthetic strategy. An iso­propyl­idene group was employed towards the synthesis of seven-membered ring imino­sugars and the title compound, C₉H₁₅N₃O₅, was crystallized as an inter­mediate, in which the THF ring is twisted and the dioxolane ring adopts an envelope conformation: the dihedral angle between the rings is 67.50 (13)°. In the crystal, the hydroxyl groups participate in O—H⋯(O,O) and O—H⋯N hydrogen-bonding inter­actions, which generate chains of mol­ecules propagating parallel to the a-axis direction. There is a notable non-classical C—H⋯O hydrogen bond, which cross-links the [100] chains into (001) sheets.

Triacetonide of Glucoheptonic Acid in the Scalable Syntheses of d-Gulose, 6-Deoxy-d-gulose, l-Glucose, 6-Deoxy-l-glucose, and Related Sugars

Ease of separation of petrol-soluble acetonides derived from the triacetonide of methyl glucoheptonate allows scalable syntheses of rare sugars containing the l-gluco or d-gulo structural motif with any oxidation level at the C6 or C1 position of the hexose, usually without chromatography: meso-d-glycero-d-guloheptitol available in two steps is an ideal entry point for the study of the biotechnological production of heptoses.