Search

The condensation of 7-benzoyloxy-4′-hydroxyisoflavone with 2-methyl-3-buten-2-ol gave 7-benzoyloxy-4′-hydroxy-3′-(3-methyl-2-butenyl)isoflavone. The hydrolysis of the alkylated isoflavone with dilute alkali afforded neobavaisoflavone [7,4′-dihydroxy-3′-(3-methyl-2-butenyl)isoflavone], which was then converted into isoneobavaisoflavone on heating with formic acid. 7-Benzyloxy-4′-hydroxyisoflavone was condensed with 2-methyl-3-buten-2-ol to give a chroman derivative, which was then converted into isoneobavaisoflavone by hydrolysis. 3′-(3-Methyl-2-butenyl)-5,7,4′-trihydroxyisoflavone was also synthesized from 7-benzoyloxy-5,4′-dihydroxyisoflavone in a similar manner.

Condensation of 7-benzoyldaidzein (III) with 2-methyl-3-buten-2-ol gave 7-benzoyl-3′-(3-methyl-2-butenyl)daidzein (IV). Hydrolysis of IV with dilute alkali gave 3′-(3-methyl-2-butenyl)daidzein (neobavaisoflavone) (I), which was converted into isoneobavaisoflavone (VI) when heated with formic acid. 7-Benzyldaidzein (VII) was condensed with 2-methyl-3-buten-2-ol to give a chroman derivative (VIII), which was converted into VI by hydrogenolysis.

Allylic oxidation of methyl 2-alkenoates with chromium trioxide in a mixture of acetic anhydride and acetic acid afforded methyl 4-oxo-2-alkenoates.

The mono p-bromobenzoate of the diol derived from α-pompene has been studied by X-ray crystal structure analysis and determined to be 9-p-bromobenzoxy-8-hydroxy-1,2,6,8-tetramethyltricyclo[5.3.1.02,6]undecane. The crystals are of the orthorhombic space group P212121, a=46.53(2), b=12.20(2), c=7.39(2) A, Z=8, and hence there are two independent molecules per asymmetric unit. The structure was solved by the heavy-atom methods, and refined by block-diagonal least-squares calculations to a final R value of 0.103 for 2493 observed reflections. The structures of the two independent molecules in the asymmetric unit are quite similar. Both molecules contain a tricyclo[5.3.1.02,6]undecane ring in which three fused rings (cyclohexane, cyclopentane, and cyclopentane) are present. The overall configuration of these three fused rings can be described as a “cis” type. The conformation of the cyclohexane ring is of a chair form, and the two cyclopentane rings exhibit envelope forms. Based on the anomalous X-ray dispersi...

During the course of investigation on constituents of liver-worts, four sesquiterpenoids showing opposite rotation, (−)-longiborneol, (−)-α-longipinene, (−)-longifolene and (+)-α-himachalene, were isolated from a Japanese liverwort. By preparation of derivatives and application of physical methods the absolute configuration of (−)-longiborneol, the main component, was elucidated as an optical antipode (I) of (+)-longiborneol isolated from higher plants.

5,2′-Dihydroxy-6,8-dimethoxyflavone, which had been proposed as the structure of skullcapflavone I isolated from Scutellaria baicalensis Georgi, was synthesized from 2-hydroxy-3,5,6-trimethoxyaceto...

5,7,2′,4′-Tetrahydroxy-5’-methoxyisoflavone (6) prepared from 2,4,2′,4′-tetrabenzyloxy-6’-hydroxy-5-methoxychalcone (2) by way of three steps was partially benzoylated to give 7-benzoyloxy-5,2′,4′-trihydroxy-5′-methoxychalcone (7). The condensation of 7 with 2-methyl-3-buten-2-ol afforded 7-benzoyloxy-5,2′,4′-trihydroxy-5′-methoxy-3′-(3-methyl-2-butenyl) isoflavone (8), which was hydrolyzed to give piscerythrone (1).

Pechmann- Kondensation des Hydroxychromans (Ia) mit dem Ketoester (II) liefert das Cumarin (IIIa), dessen Acetat (IIIc) durch Bromierung mit Bromsuccinimid (NBS) gefolgt von Dehydrobromierung mit Zn-Pulver das erforderte Benzodipyran (IVa) gibt; das Analoge (IVb) entsteht bei der Dehydrierung des Methylathers (IIIb) - zuganglich aus (Ib) und (II) - mit Dichlordicyan-p-benzochinon (DDQ).

On treatment with boron trifluoride etherate at room temperature, 6-methyl-5-hepten-2-ol and citronellol dimerized to give dioxamonocyclic compounds in a good yield.