737. isoShekkangenin and the synthesis of 4-hydroxycoumarins

Abstract

Contrary to the suggestion by Chi et al. ' isoshekkangenin is not identical with either 4 : 6; : 4'-trihydroxy-7-methoxy-or 4 : 7 : 4'-trihydroxy-5-methoxy-3-phenylcoumarin. The substitution of methyl chloroformate and potassium carbonate for ethyl carbonate and sodium in an earlier procedure provides a general method for the synthesis of 4-hydroxycoumanns, including polyhydroxy-derivatives.FROM the Chinese drug '' shekkan '' derived from Balamacartda chinensis (Linn) D.C. (identical with Pardanthus chinensii Ker Gawl l) Marmicke, Schumann, and Liss isolated a glycoside shekkanin, which was shown by Shibata4 to be identical with tectoridin, giving

Stability and Chemical Reactivity of 7-Isopropoxyisoflavone (Ipriflavone)

“…15), 226(17), 179(56), 137 (100). Ϫ Only one set of signals was detected in the 1 H and 13 C NMR spectra.…”

Tris(polymethoxyphenyl)bismuth derivatives: Synthesis and reactivity

“…The dichloride 16 was used as a substitute for the diacetate 12, that could not be prepared from bismuthane 2. Three substrates (2-naphthol 20, b-ketoester 25 and the substituted 4-hydroxycoumarin 30 [18], 4-hydroxy-5,7-dimethoxy-2H-1-benzopyrane-2-one) were selected to evaluate the reactivity of the bismuth (V) derivatives 11, 13, 14 and 16, containing polymethoxyaryl fragments as C-arylating agents.…”

Synthesis of Coumestan Derivatives via FeCl3-Mediated Oxidative Ring Closure of 4-Hydroxy Coumarins

“…Compound 2 can be prepared via intramolecular Claisen condensation of intermediate 3 , , which can be easily tracked back to the substituted methyl salicylate 4 and phenylacetic acid derivative 5 (Figure ). Alternatively, the mono- or dimethoxylated substrate 2′ (on ring A) can be obtained from intermediate 6 through methoxycarbonylation and in situ lactonization . Compound 6 can be prepared through a simple regioselective methylation of 1,3-dihydroxyl phenol derivative 7 , which can be easily formed by the reaction of polyphenols 8 with benzyl cyanide derivative or phenylacetic acid derivative 9 catalyzed by a Lewis acid (Figure ). , …”