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A palladium-catalyzed cross-coupling between 3-, 4-, and 5-halo-pyrazoles and H-phosphonates, H-phosphinates, and secondary phosphine oxides has been developed. This coupling reaction constitutes the first general method allowing the introduction of a great diversity of phosphorus substituents on the different carbons of the pyrazole ring in a one-step process.

The [3 + 2] dipolar cycloaddition of 4-halosydnones with 1-haloalkynes opens a straightforward access to 3,5-dihalopyrazoles, valuable scaffolds for the elaboration of unsymmetrically 3,5-substituted pyrazole derivatives via site-selective Pd-catalyzed cross-coupling reactions. For instance, the flexible introduction of different (hetero)aryl substituents at the C-5 and C-3 positions of the PMP-protected pyrazole nucleus was achieved in a one-pot operation via sequential reactions with various boronic acids.

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 to a large number of analogues for bioactivity screening and discovering new heterocyclic bioactive ingredients in various life science fields. [ABSTRACT FROM AUTHOR]

A new and general approach to important fluoroalkyl-substituted pyrazoles has been developed. The approach is based on the use of fluoroalkyl amino reagents and their Lewis acid activation to form a fluoroalkyl iminium salt that acts as a formal 'fluoroacyl transfer reagent'. Their interaction with readily available fluoroalkyl azines followed by spontaneous cyclization of the formed intermediates under acidic conditions leads to the formation of 3,5-disubstituted pyrazoles. The reaction is extremely versatile, high yielding, and allows quick access to pyrazoles that bear two fluoroalkyl functionalities (identical or different). These compounds are otherwise difficult to prepare. The reaction is scalable and suitable for industrial production. [ABSTRACT FROM AUTHOR]

Herein we describe the first practical method for the regioselective preparation of 3,5-bis(fluoroalkyl)pyrazoles. Starting from commercially available fluoroacetoacetates and by using (tetrafluoroethyl)dimethylamine as a convenient CF2H transfer reagent, this straightforward one-pot sequence affords highly substituted pyrazoles in good yields and excellent regioselectivity. Furthermore, these carboxylate intermediates were converted into the corresponding pyrazolic acids, which are valuable building blocks for the design of novel bioactive ingredients. [ABSTRACT FROM AUTHOR]

The difficulties to obtain convenient monocrystals of the important fungicide RPA 406194 have been overcome by a combination of solid state 13C NMR, X-ray powder diffraction and molecular modeling. The compound, a 3-aryl tautomer, crystallizes forming infinite chains of molecules bonded by N–H⋯N hydrogen bonds, leading to needle-shaped crystals. The tautomerism (equilibrium constant and energy barrier) of this compound in solution has been studied. [Copyright &y& Elsevier]

Fluoroalkyl pyrazoles, which are key building blocks in agrochemistry and promising candidates in life ‐ sciENce ‐ oriENted research, have shown much potENtial in accessing a variety of bis(fluoroalkyl)pyrazoles with tunable regioselectivity of the hydrazine addition, via two intermediates of opposed reactivity. The two strategies are represENted by one slingshot aiming at two differENt targets, with a background of crops, forests, and laboratory activities. More information can be found in the Full Paper by S. PazENok, F. R. Leroux et al. on page 11239. [ABSTRACT FROM AUTHOR]

The presented method is extremely versatile, high yielding, and allows quick access to the title compounds which are otherwise difficult to prepare. [ABSTRACT FROM AUTHOR]

A series of bromopyrazoles substituted by electron-withdrawing groups such as an ester, a trifluoromethyl group or a cyano group was involved in Pd-catalyzed phosphonylation. Moderate to good yields were obtained in the corresponding phosphonylated pyrazoles. [ABSTRACT FROM AUTHOR]

Abstract: Fluorine, the most electronegative element plays nowadays a key role in pharmaceutical, agrochemical and material sciences. It has been estimated that the number of fluorinated compounds currently under development represents some 30–50% of the total active ingredients in development. The search for new active substances with improved efficacy, lower mammalian toxicity, more favourable environmental profile and lower cost is a truly challenging task for R&D chemists within the crop protection companies. The present review will give an overview on the synthesis of pyrazoles bearing novel fluorinated substituents. [Copyright &y& Elsevier]

19 examples [ABSTRACT FROM AUTHOR]

A general method is developed for the cross-coupling of halogenated pyrazoles with H-phosphonates, H-phosphinates, and secondary phosphine oxides to produce a wide range of phosphonylated pyrazoles. [ABSTRACT FROM AUTHOR]

The first practical method for the regioselective synthesis of the title compounds is developed. [ABSTRACT FROM AUTHOR]

Review: 50 refs. [ABSTRACT FROM AUTHOR]