Synthesis of tachrosin, (±)-stachyoidin, and (±)-tephrodin, prenylflavonoids of novel type from Tephrosia polystachyoides
1977; Issue: 9 Linguagem: Inglês
10.1039/p19770000948
ISSN2050-8255
AutoresSándor Antus, Lóránd Farkas, Mihäly Nógrádi, Ferenc Boross,
Tópico(s)Phytochemical Studies and Bioactivities
ResumoTachrosin [8-(2,3-dihydro-2,2-dimethyl-3-oxo-4-furyl)-5,7-dimethoxyflavone](1) has been synthesized by oxidative rearrangement of a 1-aryl-4-hydroxypent-1-en-3-one with thallium(III) nitrate followed by cyclisation to a 4-aryl-2,2-dimethylfuran-3(2H)-one as the key step. A multi-stage transformation of the flavone (1) gave 8-(3-hydroxy-3-methyl-2-oxobutyl)-5-methoxy-7-methoxycarbonylmethoxyflavone (29), which afforded in one step the furo[2,3-c]pyran (30). Reduction of (30) with borohydride and reoxidation yielded (±)-stachyoidin (2), and treatment of (2) with lead tetra-acetate gave (±)-tephrodin (3). Sodium alkoxides are shown to catalyse the transacetalisation of α-aryl-α-aroylacetaldehyde acetals.
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