We report the first enantioselective addition of pyrazoles to 1,3-dienes. Secondary and tertiary allylic can be generated with excellent regioselectivity. Mechanistic studies support a pathway distinct from previous hydroaminations: Pd0-catalyzed ligand-to-ligand hydrogen transfer (LLHT). This hydroamination tolerates range functional groups advances field diene hydrofunctionalization.

Abstract: A facile, 1,3-dipolar cycloaddition of ethyl diazoacetate (EDA) with various activated olefins including Baylis-Hillman adducts, activated and simple alkynes to afford 3,5-disubstituted pyrazolines and pyrazoles respectively in moderate to good yields, in high regioselective manner in the presence of Indium chloride and/or DABCO is reported. All the reactions were carried out under no...

5-Hydroxy-3-oxopent-4-enoic acid esters can be efficiently transformed into the stable bis-potassium salts of the corresponding 5-hydroxy-3-oxopent-4-enoic acids, from which the sensitive acids are released in situ, the latter being converted into substituted 4-hydroxy-2H-pyran-2-ones, pyrazoles and isoxazoles under mild conditions; the efficiency of this method is demonstrated by the first syn...

A straightforward methodology for the regioselective synthesis of pyrazoles has been developed by a domino sequence based on photoclick cycloaddition followed photocatalyzed oxidative deformylation reaction. Distinguishing features this protocol include an unprecedented photoredox-catalyzed Norrish type fragmentation under green-light irradiation and use α,β-unsaturated aldehydes as synthetic e...

Abstract: Background: Biocatalysis in organic solvents has several benefits over aqueous solvents, including solubility of substrates, ease workup, separation the product, and, certain cases, reusability biocatalysts. Materials and Methods: A simple, effective, environmentally friendly technique for synthesizing pyrazoles been established, which involves cyclo condensation chalcones isonicotini...

Palladium-catalyzed amidation of five-membered heterocyclic bromides that contain multiple heteroatoms was achieved for the first time using the Pd/1 catalyst system. This system allows for efficient access to N-arylated imidazoles, pyrazoles, thiazoles, pyrroles, and thiophenes in moderate to excellent yield. Experimental results and DFT calculations point to the need for electron-rich and esp...

A novel approach towards highly functionalized fluoroalkyl pyrazoles was developed by using fluoroalkyl amino reagents in combination with a variety of fluorinated ketimines. Tuneable introduction of fluoroalkyl groups in the 3- and 5-positions was possible by using vinamidinium intermediates or the corresponding enamino ketones after hydrolysis. These high-value building blocks can give rise t...

Activated enol ethers derived from esters or the dinitrile of malonic acid, or from pentane-2,4-dione were treated with hydrazine hydrate. The structures of the obtained products - pyrazoles 5 - were studied with a focus on tautomerism and supramolecular structure. A reverse addition of the reagents led to the isolation of two novel products, namely bis-enehydrazines 6 with an unsymmetrical arr...

The nitropolychlorobutadienes 3, 4 are valuable building blocks for various amination and successive heterocyclization products. Nucleophilic substitution reactions of the partially protected, bioactive amines 1, 2 with either vinyl, imidoyl or carbonyl chlorides result in the formation of the enamines 11, 12, 13, 16, 25, the amidine 6, and the amides 20, 21, respectively. In the following, cyc...