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Ionic Liquids: Green Solvents for Chemical Processing

Two organic–inorganic hybrid polyoxometalates, consist of 1-butyl-3-methylimidazolium salts of (W 10 O 32 ) 4− and (PW 12 O 40 ) 3− polyanions were prepared and characterized by thermal analysis, X-ray diffraction, FT-IR, diffuse reflectance UV–Vis spectroscopic methods and nitrogen absorption–desorption determination (BET). These heterogeneous catalysts were used for synthesis of azlactones by the reaction of aldehydes with hippuric acid and acetic anhydride under solvent-free conditions. These catalysts were reused several times without loss of their activities.

Organic–inorganic hybrid polyoxometalates: Efficient, heterogeneous and reusable catalysts for solvent-free synthesis of azlactones

Ultrasound-promoted a green protocol for the synthesis of 2,4-diarylthiazoles under ambient temperature in [bmim]BF4

Members of the green fluorescent protein (GFP) family are widely used in experimental biology as genetically encoded fluorescent tags. Chromophores of GFP-like proteins share a common structural core: 3,5-dihydro-4H-imidazol-4-one. This review covers synthetic approaches to 3,5-dihydro-4H-imida-zol-4-ones, substituted at different positions. General, as well as specific methods, represented by single examples are considered. The most popular synthetic route to substituted 3,5-dihydro-4H-imidazol-4-ones includes synthesis of azlactones, followed by transformation into N-acyldehydroamino acids and, finally, cyclization into target heterocycles. Accordingly, the review is divided into three parts: the first part covers syntheses of azlactones, the second part covers main approaches to N-acyldehydroamino acids, and in the third part we summarize cyclizations of N-acyldehydroamino acids, as well as all other approaches to 3,5-dihydro-4H-imidazol-4-ones.

Synthesis of the chromophores of fluorescent proteins and their analogs

A facile, green and stereoselective approach for the synthesis of azlactones/oxazolones 3(a–q) has been developed. The protocol involves reaction of hippuric acid and substituted heterocyclic/aromatic aldehydes in ionic liquid [Et3NH][HSO4] to yield the desired 4-arylidene-2-phenyl-5(4H)-oxazolones in excellent yields (94–97%) with a high degree of purity. The remarkable feature of this pathway is that the ionic liquid eliminates the use of toxic and expensive acetic anhydride and is endowed with catalytic and medium engineering ability. This eco-friendly approach improved synthetic efficiency (94–97% yield), minimizing the production of chemical waste without using highly toxic reagents for the synthesis and more notably, it promoted the selectivity for Z-azlactones/oxazolones. Density functional theory (DFT) calculations revealed that the Z-isomer of compound 3a is stabilised by 2.32 kcal mol−1 more than the E-isomer. This synthetic scheme possesses diverse applicability and is compatible to a range of functional groups (electron donating/electron withdrawing).

[Et3NH][HSO4]-mediated functionalization of hippuric acid: an unprecedented approach to 4-arylidene-2-phenyl-5(4H)-oxazolones

A new, efficient and chemoselective one-pot protocol for synthesis of 4-arylidene-2-phenyl-5(4H)-oxazolones from aryl aldehyde bisulfite adducts promoted by POCL3

A one-pot procedure for the synthesis of 4-arylidene-2-phenyl-5(4H)oxazolones directly from aryl aldehyde bisulfite adducts in the absence of Ac2O in good to excellent yields using phosphoryl chloride is reported. In addition, the observed chemoselectivity can be considered as a noteworthy advantage of this method.

A New, Efficient and Chemoselective One‐Pot Protocol for Synthesis of 4‐Arylidene‐2‐phenyl‐5(4H)‐oxazolones from Aryl Aldehyde Bisulfite Adducts Promoted by POCl3.

Seyed J. Hoseini Jomor

Papers

A new, efficient and chemoselective one-pot protocol for synthesis of 4-arylidene-2-phenyl-5(4H)-oxazolones from aryl aldehyde bisulfite adducts promoted by POCL3

A New, Efficient and Chemoselective One‐Pot Protocol for Synthesis of 4‐Arylidene‐2‐phenyl‐5(4H)‐oxazolones from Aryl Aldehyde Bisulfite Adducts Promoted by POCl3.