Leprapinic acid

Deriv Leprapinic acid methyl ether, needles... 

Only two terphenylquinones, polyporic acid and thelephoric acid, are known, while pulvinic acid derivates are more numerous (calycin, epanorin, leprapinic acid, leprapinic acid methyl ether, pinastric acid, pulvinic acid, pulvinic dUactone, rhizocarpic acid, stictaurin, vulpinic acid). 

Reaction of singlet oxygen with pulvinic acid (23) by irradiation of a solution of pulvinic acid in methanol with visible light in presence of oxygen and rose bengal as a sensitizer yielded leprapinic acid (28). The reaction is considered 43) to involve electrophilic attack by singlet oxygen at the electron-rich ortho position to produce an intermediate hydroperoxide. 

Chawla, H. M., S. S. Chibber, and S. Niwas Novel Photochemical Conversion of Pulvinic Acid to Leprapinic Acid. Tetrahedron Letters 1980, 2089. 

Fully methylated pulvinic acid derivatives are cleaved by alkali to 2-aryl-3-methoxymaleic anhydrides and arylacetic acids (see Scheme 169). The products formed indicate the structure of the particular pulvinic acid (184). By reaction of vulpinic acid with 2-hydroxy-ethoxyacetamide a mixture of pulvinic acid monolactam (547) and pulvinic acid dilactam (548) (see Scheme 170) has been obtained (65(5). Further new pulvinic acid derivatives are vulpinic acid isopropyl ether (549) (660) and the pyridazine 550 (600) (see Schemes 171 and 172). Chawla et al. (67) investigated the photochemical conversion of pulvinic add to leprapinic acid. 

Leprapinic acid derivatives Gram positive and Gram negative bacteria (601)... 

Raju KR, Appa Rao AVN, Rao PS (1985) Leprapinic Acid Derivatives with Antibacterial Activity. Fitoterapia 56 221... 

---