A new general synthesis of hydroxy- and methoxy-isoflavanones

Unexpected formation of hydroxybiphenylmethane derivatives and some new observations on Labat test

“…Further, we present some new observations on Labat test that unequivocally expands its scope and versatility. Among the synthetic methods reported for the preparation of isoflavanones [1], the method of Jain and Mehta [16] seemed to be quite promising for methoxy as well as hydroxyisoflavanones. However, in order to develop a more easy and straightforward approach for the synthesis of isoflavanones, we envisaged to shorten the described pathway by combining the reported four steps into a one-pot reaction, thereby trying to avoid the necessary purifications and thus improving the overall yields.…”

Enzyme-Catalyzed Chemoselective Transesterification Reactions on Hydroxymethylated Phenolic Compounds

“…As in the case of acetylation of hydroxymethylated phenols, PPL and CRL exhibited 100% selectivity for the acetylation of aliphatic hydroxyl group with respect to phenolic hydroxyl group in hydroxymethylated aryl alkyl ketones. Thus, incubation of compounds 6 and 7 with PPL in THF afforded the monoacetoxy products, 3-acetoxy-1-(4Ј-hydroxyphenyl)-2-methylpropanone (15) and 3-acetoxy-2-ethyl-1-(2Ј,4Ј-dihydroxyphenyl)propanone (16) in 65 and 55% yields in 12 and 38 h ( Table 1), respectively. It has been observed that PPL in THF catalyzes the acetylation of aliphatic hydroxyl group of 6 and 7 faster than CRL in DIPE, the rate of selective (7) dihydroxyphenyl)propanone (16) 3-Hydroxy-1-(2Ј-hydroxy-4Ј-…”

“…Attempts to prepare di/triacylated derivatives of 7, 8, and 9 resulted in the enolization of ketonic carbonyl group and subsequent formation of the corresponding enolic peracetates as per our earlier observation in similar compounds (18). The hitherto unknown compounds 7, 9, 24, and 26 were characterized on the basis of their spectral analysis and the known compounds 6 and 8 were characterized by their spectral analysis and comparison with the data reported in the literature (14,16).…”

“…Further, 2-ethyl-3-hydroxy-1-(2Ј,4Ј-dihydroxyphenyl)propanone (7) was prepared by hydroxymethylation of 4-benzyloxy-2-hydroxybutyrophenone (25) (15) as above, followed by debenzylation of the hydroxymethylated ketone, 1-(4Ј-benzyloxy-2Ј-hydroxyphenyl)-2-ethyl-3-hydroxypropanone (26) by catalytic hydrogenation (Scheme 1). The hydroxypropanones, 3-hydroxy-1-(2Ј-hydroxy-4Ј-methoxyphenyl)-2-phenylpropanone (8) and 3-hydroxy-1-(2Ј-hydroxyphenyl)-2-(4Љ-methoxybenzyl)propanone (9) were prepared by reacting 2-hydroxy-4-methoxydesoxybenzoin (16) and 2Ј-hydroxy-4-methoxydihydrochalcone (17) with ethoxymethyl chloride in the presence of dry potassium carbonate in dry acetone in 65 and 70% yields, respectively. The diacetate, 3-acetoxy-1-(4Ј-acetoxyphenyl)-2-methylpropanone (24) was prepared as in the case of hydroxymethylated phenols in 98% yield.…”

Synthesis and Anti-tumor Activities of Novel Oxazinyl Isoflavonoids

“…Compounds 3a-c, 4a-c, and 8a-c were synthesized according to the literature. 6,8,9) . and a 37% formaldehyde solution (1.4 g, 16.6 mmol) were dissolved in 1,4-dioxane (1 mL) at 45°C and stirred for 15 min, and then the resulting mixture was added to a solution mixture of 4a-c (13.8 mmol) in 1,4-dioxane (35 mL).…”