51181-43-2

Upstream product

• 101606-34-2 3,4-bis(bromomethyl)-2,5-diphenylfuran 
• 78211-50-4 2,3-dimethyl-1,4-diphenyl-but-2t-ene-1,4-dione 
• 34733-55-6 2,3-dimethyl-1,4-diphenyl-butane-1,4-dione 
• 33375-02-9 2,3-dimethyl-1,4-diphenyl-but-2c-ene-1,4-dione 
• 64-19-7 acetic acid 
• 10035-10-6 hydrogen bromide 
• 135-19-3 β-naphthol 
• 955-83-9 2,5-diphenylfuran 
• 4518-65-4 (1-methoxyprop-1-en-1-yl)benzene 
• 2114-00-3 2-bromo-1-phenyl-1-propanone 
• 73893-85-3 (2R*,3S*)-2,3-dimethyl-1,4-diphenylbutane-1,4-dione 
• 34733-55-6 (2R*,3R*)-2,3-dimethyl-1,4-diphenylbutane-1,4-dione 

Downstream Products

• 33375-02-9 2,3-dimethyl-1,4-diphenyl-but-2c-ene-1,4-dione 
• 78211-50-4 2,3-dimethyl-1,4-diphenyl-but-2t-ene-1,4-dione 

Relevant academic research and scientific papers

Ionic liquid as catalyst and reaction medium: A Simple and Efficient Procedure for Paal-Knorr furan synthesis

The ionic liquid 1-butyl-3-methyl-imidazolium hydrogen sulfate, [bmim]HSO4, efficiently catalyzes Paal-Knorr furan synthesis without any organic solvent. A wide range of aliphatic and aromatic 1,4-diketones easily undergo condensations to form furan derivatives, providing a general and convenient procedure. The Paal-Knorr reaction of ester-substituted 1,4-diketones is first reported. The ionic liquid can be recovered and reused for subsequent runs without any appreciable loss of efficiency.

Reaction of nitrous oxide with cyclopentadienyl complexes of cobalt, rhodium, and titanium

The reaction of nitrous oxide with some cyclopentadienyl compounds of cobalt, rhodium, and titanium was studied. The corresponding furans were obtained in low to moderate yields.

Preparations of Furans from α-Bromo Ketones and Enol Ethers Catalyzed by a Rhenium(I) Nitrogen Complex

By the catalytic use of a rhenium(I) nitrogen complex, [ReCl(N2)(PMe2Ph)4], α-keto radicals are generated from α-bromo ketones and react with vinyl ethers and silyl enol ethers intermolecularly. Various substituted furans, including tetrasubstituted furans such as furoguaiacin, are prepared by this method.

Intermediates in the Paal-Knorr Synthesis of Furans

New experimental evidence for the mechanism of the Paal-Knorr reaction involving the acid-catalyzed cyclization of a 1,4-diketone to form a furan is reported.In aqueous or alcoholic solutions containing hydrochloric acid and in chloroform containing boron trifluoride-etherate d,l- and meso-3,4-diethyl-2,5-hexanediones (2r and 2m) cyclize at unequal rates; the stereochemical configuration of the unchanged dione is preserved during the reaction.This disagrees with commonly accepted mechanism involving the ring closure of the rapidly formed monoenol (11b) followed by loss of water.A pathway involving the rapid protonation of one of the carbonyls followed by the electrophilic attack on the protonated carbonyl by the enol being formed at the other carbonyl group (10c) is proposed to account for the difference in reaction rates between the diastereomers of 3,4-disubstituted 2,5-hexanediones (1-3).The following results also seem to support the intermediacy of 10c.The presence of two isopropyl groups in 3,4-diisopropyl-2,5-hexanedione (3) considerably reduces the rate of cyclization.The catalytic constants kH(+) for the cyclization of 2r and 2m are larger than the constants for enolization of methyl ketones.The diastereomers of 2,3-dimethyl- and 2,3-diethyl-1,4-diphenyl-1,4-butanediones (4 and 5), which could enolize only toward the center of the molecule, also react at different rates.The d,l and meso dideuterio analogs (d2-4r and d2-4m) exhibit a primary isotope effect during cyclization.The order of cyclization of 1,4-diphenyl-1,4-butanedione (6) and its analogs (7-9) reveals that the presence of electron-donating groups facilitate the reaction.