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Up to now, derivatives of usnic acid were only prepared by classical methods of refluxing in organic solvents for hours. In this study, we examined the condensation reaction of usnic acid with o-toluidine under microwave irradiation condition which gave good yield in a short time. The obtained optimal condition was applied to prepare some other derivatives of (+)-usnic acid. | TAÏP CHÍ PHAÙT TRIEÅN KH&CN, TAÄP 18, SOÁ T3 - 2015 Preparation of some derivatives of (+)-usnic acid with aromatic amines under microwave irradiation condition Nguyen Trung Giang Tan Tao University Luu Hoang Duy Khuong Nguyen Kim Phi Phung University of Science, VNU–HCM (Received on December 12 th 2014, accepted on August 12 th 2015) ABSTRACT Up to now, derivatives of usnic acid were microwave irradiation condition which gave only prepared by classical methods of good yield in a short time. The obtained refluxing in organic solvents for hours. In this optimal condition was applied to prepare some other derivatives of (+)-usnic acid. study, we examined the condensation reaction of usnic acid with o-toluidine under Key words: (+)-Usnic acid, o-toluidine, microwave irradiation condition, condensation reaction, cyclopentyl methyl ether. INTRODUCTION Usnic acid (1), 2,6-diacetyl-7,9-dihydroxy8,12-dimethyl-1,3-(2H,12H)-dibenzofurandione, is a naturally occurring dibenzofurane derivative found in several lichen species. Usnic acid was identified in many genera of lichens including Alectoria, Cladonia, Evernia, Parmotrema, Ramalia, and Usnea, and it exists in one of two enantiomers which differ in the orientation of the methyl group located in position 12. It was first isolated by the German scientist W. Knop in 1844 [1]. Me O Me O HO Me OH Me OH O Me THF/EtOH 50 oC 5h O HO Me In 2006, Sophie Tomasi and co-workers [3] performed condensation reaction of usnic acid with some amines, diamines and triamines. In 2008 and 2009, similar processes were performed by some authors [4]. O O R-NH2 Usnic acid possesses a wide range of interesting biological properties. It is a potent antibiotic effective against Gram-positive bacteria, including Mycobacterium tuberculosis, Staphylococcus, Streptococcus and Pneumococcus. It also exhibits antiviral, antiprotozoal, antimitotic, anti-inflammatory and anticancer [2]. O Me OH O NH-R Me Fig 1. Condensation reaction of
