A series of key intermediates of quercetin analogues were designed and synthesized in this paper.Acetophenone derivatives were got by using phloroglucinol as raw material through the Hoesch reaction and dimethyl sulphate to protect its 4,6-dihydroxyl,from which three key intermediates were synthesized through two different pathways:5,7-dimethoxy-2-cyano-benzopyran-4-one(6),5,7-dimethoxy-benzopyran-4-one(8),5,7-dimethoxy-2,3-epoxy-benzopyran-4-one(9).All the compounds were confirmed by MS and 1H-NMR.
The synthetic route of 3’-amino carboxylate hydrochloride of quercetin is improved.Using benzyl bromide to partly protect the hydroxyl groups,the protected quercetin then react with a series of Boc protected amino acids to afford the 3’-amino carboxylate,hydrogenised and treated with HCl(g),a series of 3’-amino carboxylate hydrochloride of quercetin are synthesized in good yields.The structures of these compounds are confirmed by means of their m.p.,mass spectra and 1H NMR.
Amino acid benzyl ester p-toluenesulfonic acids were synthesized under microwave irradiation condition by reaction of four amino acids with benzyl alcohol and p-toluenesulfonic acid,and then reacted with the N-phthaloyl-L-glutamic anhydride to yield compound 3a-d,hydrogenised and treated with NH3(g) to obtain the target compounds—thalidomide ammonium salt derivatives.The microwave-assisted method was used to synthesis the thalidomide amino acid benzyl ester p-tolunensulfonic acid,the reaction time was brought down with improved yield as compared with conventional heating method.The structures were comfirmed by MS,1H-NMR and elemental analysis.
The hydrochloride of 1-(1-amino-3-methyl)butyl borate pinacol is prepared by using the isobutylbromide to form the Grignard agent.The product is protected with the pinacol,then reacted with the lithium diisopropylamide and the anhydrous zinc chloride.Finally,the product is synthesized in the existence of the LHMDS.All the compounds are confirmed by MS and 1H-NMR.
