Simple Synthesis of 5-Substituted Resorcinols:  A Revisited Family of Interesting Bioactive Molecules

Abstract

The reaction of 3,5-dimethoxybenzyl trimethylsilyl ether (3) with different aldehydes (n-PrCHO, n-C(11)H(23)CHO, MeCHO, PhCHO) in the presence of lithium powder and a catalytic amount of naphthalene (4 mol %) gave, after hydrolysis, the expected alcohols 4 in moderate yields. The dehydroxylation of these compounds through the corresponding mesylates 5 or directly from benzylic derivatives by catalytic hydrogenation, afforded compounds 6, which are finally demethylated to yield 5-alkyl-3,5-dihydroxyresorcinols, such as olivetol (7a), grevillol (7b), 1,3-dihydroxy-5-propylbenzene (7c), or dihydropinosilvine (7d). Dehydration of alcohol derivatives 4 followed by demethylation led to hydroxylated stilbene-type structures, such as pinosilvine (9d), resveratrol (9e), or piceatannol (9f), which in some cases can be hydrogenated to give saturated molecules such as combretastanin B-4 tetramethyl ether (6f) or chrysotobibenzyl (6g). Finally, when the naphthalene-catalyzed lithiation of compound 3 was performed in the presence of other electrophiles [Me(3)SiCl, t-BuCHO, CH(3)(CH(2))(4)CHO, 4-Me(3)SiOC(6)H(4)CHO, (CH(2))(5)CO, PhN=C=O, PhN=CHPh], the expected reaction products 12 were isolated, after hydrolysis.

Total antioxidant capacity and content of flavonoids and other phenolic compounds in canihua (Chenopodium pallidicaule): An Andean pseudocereal

“…They are not common in nature but several plant families contain 5-alkyl-resorcinols, for instance Graminae, Gink- [22] l) Saura-Calixto and Goaei [21] m) Perez-JimØnez and Saura-Calixto [18] goaceae and Anacardiaceae [35]. However, the 5-alkyl resorcinols had different retention times at HPLC compared with the substances found in the present study, are primarily acetone-soluble and have two UV maxima at 275 and 282 nm [36], and thus it seems unlikely that the compounds observed here are 5-alkylresorcinols.…”

Practical generation of 3,5‐dimethoxybenzyllithium: application to the synthesis of 5‐substituted‐resorcinols

“…Conversion of these alcohols into the corresponding, biologically active, stilbenic resorcinols, namely pinosilvine and resveratrol, was described recently. 6 …”

“…3 -5 Accordingly, there is a continuous search for new approaches to their synthesis. 4,6 -9 Recently, Yus and co-workers 6 reported on the generation of 3,5-dimethoxybenzyllithium as a useful intermediate in the synthesis of such compounds.…”

A Practical Method to Stereospecifically Synthesize trans‐Stilbene Derivatives

“…It is a well-documented reaction, which can stereospecifically lead to the formation of the trans-isomers in decent yields. 4,7 However, the lack of efficient methods to prepare the 1,2-diarylethanols greatly limits the application of this dehydration method. We report herein a practical one-pot reaction sequence to stereospecifically prepare trans-stilbene derivatives with high yields through 1,2-diarylethanols.…”