Facile Approaches to 2-Deoxy-d-glucose and 2-Deoxy-α-d-glucopyranonucleosides from d-Glucal

Convenient and stereoselective methods for the preparation of 2-deoxy-d-glucose and purine 2-deoxy-α-d-glucopyranonucleosides were developed. Halogen-mediated O-glycosidation of d-glucal by bromine in MeOH followed by reductive removal of the halo group and hydrolysis of methoxy group by zinc in saturated aqueous sodium dihydrogen phosphate gave 2-deoxy-d-glucose. Treatment of 3,4,6-tri-O-acetyl-d-glucal with IBr and 2,6-dichloropurine based on haloetherification and subsequent reductive removal of iodine and deprotection allowed the isolation of purin-9-yl 2-deoxy-α-d-glucopyranonucleoside. Preparation of several purin-9-yl 2-deoxy-α-d-glucopyranoside derivatives is also reported. Their configuration was confirmed by single crystal X-ray analysis of the key intermediate 2,6-dichloro-9-(2-iodo-2-deoxy-α-d-glucopyranosyl)purine.

Improved synthesis of gastrodin, a bioactive component of a traditional Chinese medicine

Highly practical synthesis of gastrodin has been developed using penta-O-acetyl-b-D-glucopyranose and p-cresol as glycosyl donor and glycosyl acceptor, respectively, in four steps with 58.1% overall yield. At the initial step, the penta-O-acetyl-b-D-glucopyranose was treated with p-cresol in the presence of BF3.Et2O as catalyst to generate 4-methylphenyl 2,3,4,6-tetra-O-acetyl-b-D-glucopyranoside in 76.3% yield. Furthermore, this product was subjected to radical bromination with NBS to provide 4-(bromomethyl) phenyl 2,3,4,6-tetra-O-acetyl-b-D-glucopyranoside in 91% yield. Subsequently, reaction of 2,3,4,6-tetra-O-acetyl-b-D-glucopyranoside with a solution of acetone and saturated aqueous sodium bicarbonate led to 4-(hydroxylmethyl) phenyl 2,3,4,6-tetra-O-acetyl-b-D-glucopyranoside in 93% yield. Finally, global deprotection of 4-(hydroxylmethyl) phenyl 2,3,4,6-tetra-O-acetyl-b-D-glucopyranoside under Zemplen conditions furnished gastrodin in 90% yield. Compared to the previously reported methods, this protocol has advantages of operational simplicity, chromatography-free separation, high overall yield, inexpensive and common reagents as well as less waste pollutants, rendering it an alternative suitable for industrial production.

Orientation by gravid Australian sheep blowflies, Lucilia cuprina (Diptera: Calliphoridae), to fleece and synthetic chemical attractants in laboratory bioassays

Gravid females of Lucilia cuprina (Wiedeman) in a laboratory cage orientated positively to samples of fleece. Newly-wetted fleece was significantly more attractive than dry fleece, an effect resulting from the action of water on the fleece and not just addition of water vapour to the volatile fleece kairomones. Fleece contaminated with serous exudate, resulting from myiasis by L. cuprina, was much more attractive than wet, uncontaminated fleece from the same sheep. Kairomones from wetted fleece consistently augmented the attractive effects of 2-mercaptoethanol and indole in separate experiments, and of hydrogen sulphide (released from saturated aqueous sodium sulphide solution) in one trial out of three, but not overall. It is suggested that volatile fleece kairomones play a part in eliciting orientation to sheep by gravid L. cuprina. Fleece kairomones may augment the efficacy of kairomones released by putrefactive conditions in the fleece, which are known to predispose sheep to fly strike. They may also provide an input which helps to retain L. cuprina populations in the sheep’s peridomestic precinct.