Acid-Catalyzed Reactions of Aromatic Aldehydes with Ethyl Diazoacetate:  An Investigation on the Synthesis of 3-Hydroxy-2-arylacrylic Acid Ethyl Esters

Abstract

Several commercial Lewis acids, including those of the Bronsted type, specifically HBF(4).OEt(2), are able to catalyze the reaction between aromatic aldehydes and ethyl diazoacetate to produce 3-hydroxy-2-arylacrylic acid ethyl esters and 3-oxo-3-arylpropanoic acid ethyl esters. Reactions catalyzed by the iron Lewis acid [(eta(5)-C(5)H(5))Fe(+)(CO)(2)(THF)]BF(4)(-) (i.e., 1) have the best yields and greatest ratio of 3-hydroxy-2-arylacrylic acid ethyl ester. The product distribution of 1 is not affected in the presence of Proton Sponge, but is dependent on temperature and the nature of the substrate aldehyde, whereas the activity of HBF(4).OEt(2) is affected by the presence of Proton Sponge and is reactive at temperatures as low as -78 degrees C. Consequently, both 1 and HBF(4).OEt(2) are valuable catalysts in producing important 3-hydroxy-2-arylacrylic acid ethyl esters as precursors to biologically active compounds.

Flame retardancy mechanisms of triphenyl phosphate, resorcinol bis(diphenyl phosphate) and bisphenol A bis(diphenyl phosphate) in polycarbonate/acrylonitrile–butadiene–styrene blends

“…37 This reaction is believed to proceed through an addition/hydride migration route. Hossain and co‐workers described trends across a range of Lewis acids and Brønsted acids, and revealed that in contrast to the selectivity for β‐ketoester provided by SnCl 4 , many other Lewis acids and HBF 4 ⋅OEt 2 provided either low selectivity, or favored a 3‐hydroxy acrylate product 38…”

Synthesis and characterization of amine complexes of the cyclopentadienyliron dicarbonyl complex cation, [Cp(CO)2Fe]+

“…The cationic complexes of type, [CpFe(CO) 2 L] + (L = labile ligand) [1][2][3][4] are an important class of transition metal compounds that have been extensively utilized in synthesis [2,[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and catalysis [3,14,[22][23][24][25][26][27][28][29][30][31][32][33]. A particular example is the ethereal complex, [CpFe-(CO) 2 (THF)]BF 4 [34] in which the labile tetrahydrofuran (THF) is coordinated to the metal centre through the oxygen atom.…”

“…A particular example is the ethereal complex, [CpFe-(CO) 2 (THF)]BF 4 [34] in which the labile tetrahydrofuran (THF) is coordinated to the metal centre through the oxygen atom. This complex has been proven to be an essential precursor in the synthesis of various cyclopentadienyliron complexes [4,[10][11][12][13][15][16][17][18][19][20]35], as well as catalysts in various organic syntheses such as the [2+2] cycloaddition of alkenes [36], Diels-Alder reactions [37,38], cyclopropanation [27,[31][32][33], epoxidation [29,30] and aziridination [25][26][27][28], among others [3,[22][23][24]27,29,39]. In all these reactions THF is easily displaced by the desired substrate to form either the desired intermediate or desired end product.…”

Iron‐Catalyzed Ferrocenylmethanol OH Substitution by S, N, P, and C Nucleophiles

“…The absence of catalyst deactivation is remarkable as amine complexes of Fp + are known and can be prepared from [Fp(Et 2 O)][BF 4 ] and alkylamines 25. On the other hand, it has been reported that Fp + also acts as a catalyst in the presence of 1,8‐bis(dimethylamino)naphthalene, which is potentially able to deactivate it 26…”