Substituent Effect on the Formation of Arylindanes by Dimerization of Ferulic Acid and its Related Compounds

Abstract

Homodimerization and crossed-dimerization reactions for ferulic acid and related compounds in an acidic ethanol solution were investigated via a formal [3 + 2] cycloaddition reaction. Arylindanes, as the major products, were produced from some of the acids with hydroxy group and/or methoxy groups at the para and meta positions of the phenyl ring. The formation of arylindane required the following consecutive reactions: (I) protonation of the first produced ester to afford to a benzylic cation, (II) which reacts with another ester to afford a new benzylic cation, and (III) followed by cyclization to produce the dimer. It is suggested that the para-substituent promoted both step I and step II and the meta-substituent accelerated step III. To rationalize the selectivity of homodimerization, the stability of the benzyl cations and the specific electron distribution on the molecular surface of each ester is discussed based on the results of the molecular orbital calculations.

Green synthesis of ethyl cinnamates under microwave irradiation: photophysical properties, cytotoxicity, and cell bioimaging

“…After purification either by chromatography column or crystallization, the compounds 3a–f were obtained predominantly as E isomers with 73% to 96% yields ( Scheme 1 ). Under these conditions, it was possible to obtain the desired compounds in a one-step reaction, without catalysts, and with improved yields compared to the ones reported in the literature (for compounds 3a and 3d, Y. Mizuta, 38 reported 46% and 49% yield respectively; for compound 3c, J. Lu, 43 reported 89% yield, for compound 3b, X. Zeng, 42 reported 97% yield, and for compound 3f, E. Nomura, 44 reported 66% yield). Therefore, we are now reporting an eco-friendly experimental protocol for the synthesis of these compounds.…”

“…1 H NMR (400 MHz, CDCl 3 ): d 1.17 (t, J = 7.1 Hz, 6H, (CH 3 CH 2 )N), 1.32 (t, J = 7.1 Hz, 3H, OCH 2 CH 3 ), 3.38 (q, J = 7.1 Hz, 4H, (CH 3 CH 2 )N), 4.23 (q, J = 7.1 Hz, 2H, OCH 2 CH 3 ), 6.19 (d, J = 15.8 Hz, 1H, CHC]O), 6.62 (d, J = 8.9 Hz, 2H, H arom ), 7.39 (d, J = 8.9 Hz, 2H, H arom ), 7.61 (d, J = 15.8 Hz, 1H, ]CHC 6 H 4 ). 13 44…”

Ferulic Acid Dimers as Potential Antiviral Agents by Inhibiting TMV Self-Assembly

“…Second, several ferulic acid esters were synthesized using the previous method, dimerized, and hydrolyzed based on the reported method to obtain compounds B1–B4 (Scheme ). , Third, compound B1 was etherified with different bromo-hydrocarbons to prepare compounds C1–C4 , and compound C2 / C3 was hydrolyzed to obtain compound C5 / C6 (Scheme ). Finally, compound C1 / C2 was oxidized with a modified method to obtain compound intermediate 2a / 2b with desired yields, which was then condensed with hydroxylamine and thioalcohol to synthesize compounds D1–D6 and E1–E7 , respectively (Scheme ).…”

“…As shown in Scheme , the compounds A1–A5 were synthesized using the optimized method on the basis of the reported method. , The mixture of ferulic acid (20 mmol) and alcohol (20 mL) was stirred at room temperature, and then TiCl 4 (24 mmol) was added and stirred for another 12 h. Upon completion of the reaction, the excess alcohol was recovered, and the residue was separated by column chromatography (petroleum ether/ethyl acetate = 3:1) to obtain compounds A1–A5 . Then, 0.2 M LiOH solution was added to the solution of A1 (10 mmol) in 20 mL of ethanol, and the mixture was refluxed for 6 h to remove the solvent under reduced pressure, a small amount of water was added, and then the mixture was acidified by dropwise addition of 5% aqueous HCl, filtered, and washed with cold water.…”