The Synthesis Of Glycosyl Nitrones And The Reaction Of Organoaluminium Reagents With Aromatic Aldehydes

In this thesis, we mainly focus on the synthesis of glycosyl nitrones and the reaction of organoaluminium reagents with aromatic aldehydes.Chapter one Research progress of nitrones compoundsThis chapter mainly introduced synthetic methods and their organic and biological application of nitrones. There are kinds of standard synthetic routes nitrones. Commonly, oxidation of N,N-disubstituted hydroxylamines and condensation of aldehyde or ketone with hydroxylamines are the most used method. Still, new methods, such as microwave irradiation and ultrasonic method appeared in rencent years. As a 1,3-dipole reagents, nitrones can undergo 1,3-cycloaddition reactions with various alkenes or alkynes to construct different isoxazole compounds, which was widely used in total synthesis of natural products. In addition, nitrones were good agents for trapping free radical and thus have therapeutic application.Chapter two Research in synthesis of nitrone glucosideThe introduction of a sugar moiety into nitrone can both improve the solubility of nitrone in water and reduce their toxicity towards living cell. Glucose and lactose were selected as the raw materials which underwent acylation and bromination to give correspondingα-glycosyl bromide. Reaction of the glycosyl bromide with hydroxylated aromatic aldhydes gives the corresponding O-glycosylated benzaldehyde which condensed with hydroxyl amine to give the target nitrones. 16 target compounds were synthesized and their structure were further confirmed by IR, 1~H NMR, MS, and (13)~C NMR. In order to determine their absolute configuration, the X-ray diffraction study of a single-crystal of 3i was taken, combined with coupling constant of sugar ring C1, showed that all compounds with trans-configuration and the glycosidic bond wasβ- configuration.Chapter 3 Development of isochroman compoundsIn this chapter isocromans and isochromans with substituents in the dihydropyran ring, isochroman with substituents in the aromatic ring, isochroman with substituents both in the aromatic and dihydropyran rings were shortly reviewed.Chapter 4 Investigation of reaction of organic aluminum reagent with aromatic aldhydes.According to different conditions, prepared organic aluminum reagent reacting with aromatic can produce both of Isochroman and ketone compounds. Using optimal conditions, we selectivily produced 11 Isochroman and 5 ketone. Products were confirmde by IR, 1~H NMR, (13)~C NMR, MS. In order to further determined the absolute configuration of Isochroman. As the model compounds, single crystal of compounds 1F and 1D were obtained. Results show that the products exist in trans-configuration for aromatic aldhydes without heteroatom and for aldhydes from hetero aomatic compound, the products had cis-configuration. The reason for this might be that the heteroatom can coordinate to the metallic ion.