Convenient synthesis of 3,3,3-trifluoropropanoic acid by hydrolytic oxidation of 3,3,3-trifluoropropanal dimethyl acetal

A convenient and efficient method for preparing 3,3,3-trifluoropropanoic acid (1) is reported. The starting material is 1-chloro-3,3,3-trifluoropropene (2) that can be easily transformed into 3,3,3-trifluoropropanal dimethyl acetal (4) on treatment with methanol and KOH followed by acid-catalyzed addition of methanol. Direct transformation of 4 into 1 was efficiently achieved with 30% aqueous hydrogen peroxide (4.0 equiv.) in the presence of FeCl₃ (0.025 equiv.) and hydrochloric acid (0.5 equiv.).     

Synthesis of 3,3,3-trifluoroprop-1-enyl compounds from some enolizable aldehydes

2,2,2-Trifluoroethyldiphenylphosphine oxide [Ph₂P(O)CH₂CF₃] (2) is known to give no Horner reaction product with enolizable aldehydes. We found, however, that some enolizable aldehydes such as N-Boc-pyrrolidine-2-aldehyde (9) gave the expected 3,3,3-trifluoroprop-1-enyl compounds by reaction with 2. The products could be further transformed to some 2,2,2-trifluoroethyl-substituted nitrogen-containing heterocycles by using radical cyclization or Heck reaction.     

Bismuth compounds in organic synthesis. Bismuth nitrate catalyzed chemoselective synthesis of acylals from aromatic aldehydes

Aromatic aldehydes are smoothly converted into the corresponding acylals in good yields in the presence of 3-10 mol% Bi(NO₃)₃·5H₂O. Ketones are not affected under the reaction conditions. The relatively non-toxic nature of the catalyst, its ease of handling, easy availability and low cost make this procedure especially attractive for large-scale synthesis.     

A one-pot synthesis of 3-arylglutaric anhydrides by reaction of ketene with aromatic aldehydes and ketones

Aromatic aldehydes and ketones react with ketene under Lewis acid catalysis to produce β-lactones, which in situ react with another molecule of ketene to produce 3-arylglutaric anhydrides. The mechanism, scope, and limitation of this one-pot synthesis of 3-substituted glutaric anhydrides are discussed.     

An efficient and versatile synthesis of aromatic nitriles from aldehydes

A simple and direct method has been developed for synthesis of nitriles based on one-pot reaction of aromatic aldehydes with three different kind of reagents:CeCl₃7H₂O/KI/H₂O₂,CeCl₃·7H₂O/KI/UHP and（NH₄）₂Ce（NO₃）₆/KI/H₂O₂ in aqueous ammonia.     

Direct asymmetric aldol reaction of acetophenones with aromatic aldehydes catalyzed by chiral Al/Zn heterobimetallic compounds

Chiral Al/Zn heterobimetallic complexes are effective catalysts for the direct highly enantioselective aldol reaction of acetophenones with aromatic aldehydes. The Al site in the complex acts as a Lewis acid to activate aldehyde, whereas ethylzinc alkoxide plays a role of a Brønsted base to form a reactive zinc enolate with acetophenone. Distinct nature of two different metals contributes to the efficient direct asymmetric aldol reaction.     

Convenient synthesis of mesitylene-bridged hexaazamacrobicyclic compounds

Two mesitylene-bridged hexaazamacrobicyclic ligands 1 and 2 were prepared by a three-step process from available 2,4,6-tris(bromomethyl)mesitylene ( 9 ) and N, N'-di-p-tosylethylenediamine and N, N'-di-p-tosyl-1,3-diaminopropane. First, mono-BOC-protected ditosylamines 5 and 6 were prepared by treating the two diamines with BOC-O-BOC. These mono-BOC-protected diamines were treated with the tris(bromomethyl)-mesitylene followed by deprotection to give 2,4,6-tris(2,5-ditosyl-2,5-diazapentyl)mesitylene ( 3 ) and its 2,6-diazahexyl analog 4 . These latter intermediates were treated with tris(bromomethyl)mesitylene to give the mesitylene-bridged hexaazamacrobicycles. This three-step synthesis replaces the reported nine-step process.     

Continuous-flow synthesis of nitriles from aldehydes via Schmidt reaction

Using continuous-flow synthesis of nitriles by Schmidt reaction, a variety of aldehydes could be smoothly transformed into the desired nitriles in good to excellent yields. The mild reaction conditions and the flowing reaction system greatly improved the safety and make the reaction easy to scale up.     

Chromium-mediated synthesis of polycyclic aromatic compounds from halobiaryls

[reaction: see text] Reaction of 2,2'-dihalobiphenyl with butyllithium followed by the addition of chromium(III) chloride and alkynes afforded the corresponding phenanthrene derivatives via formal [4 + 2] cycloaddition. A variety of alkynes could be used for this reaction, such as alkyl, aryl, silyl, and alkoxycarbonyl alkynes. Repetitive process of the reaction gave more extended polycyclic compounds such as benzo[g]chrysene and azacyclopentaphenalene derivatives.     

Original synthesis of oxiranes via TDAE methodology: reaction of 2,2-dibromomethylquinoxaline with aromatic aldehydes

We report herein the reaction of 2,2-dibromomethylquinoxaline 2 with aromatic aldehydes 3a-g in the presence of TDAE. These reactions lead to a mixture of cis/trans-isomers of corresponding oxiranes 4a-g in good yields. The stereoselectivity of the reaction was sensitive to steric hindrance.     

Enantioselective pinacol coupling reaction of aromatic aldehydes catalyzed by chiral vanadium complexes

The asymmetric pinacol coupling of aromatic aldehydes by chiral salan–vanadium complexes as effective catalysts is reported. Chiral 1,2-diols were obtained with high diastereoselectivities (up to 90/10) and moderate to high enantioselectivities (up to 82% ee). The possible mechanism of the pinacol coupling reaction is also discussed.     

A novel synthesis of 2,3-dihydrooxazoles from dimethyl n-ethoxycarbonylmethyliminodithiocarbonate and aromatic aldehydes

We report the synthesis of 5-aryl-2-ethoxycarbonyl-4-methylthio-2,3-dihydrooxazoles from a cyclocondensation reaction betweeen dimethyl N-ethoxycarbonylmethyliminodithiocarbonate and aromatic aldehydes.