An improved preparation of 3,5-bis(trifluoromethyl)acetophenone and safety considerations in the preparation of 3,5-bis(trifluoromethyl)phenyl Grignard reagent

Grignard reagent formation via C-F bond activation: a centenary perspective

Examples of Grignard reagents obtained by C-F bond activation with magnesium have kept appearing in the literature over the last century. Due to the high bond dissociation energy of the C-F bond, a lot of effort has been invested in the preparation of highly active forms of magnesium for this purpose. Originally, magnesium activation was achieved by the application of additives, notably iodine. Later work focused on the generation of highly active magnesium powder by reduction of magnesium salts with alkali metals ("Rieke magnesium"). Modern approaches to the problem involve the application of Mg(I)-Mg(I) dimers and C-F bond activation performed by a transition metal catalyst followed by transmetallation with a magnesium salt. The purpose of this article is to provide an overview of fluoro-Grignard reagent preparation approaches reported to date.

A practical ortho-acylation of aryl iodides enabled by moisture-insensitive activated esters via palladium/norbornene catalysis

Herein reported is a practical Catellani-type ortho-acylation of aryl iodides enabled by employing moisture-insensitive esters as the electrophile via C(O)–O bond cleavage.

Solvent-free anhydrous Li+, Na+ and K+ salts of [B(3,5-(CF3)2C6H3)4]−, [BArF4]−. Improved synthesis and solid-state structures

We report an alternative, improved, multigram scale (∼20 g, 60–70% yield) preparation of solvent-free anhydrous Li[BAr^F₄], Na[BAr^F₄] and K[BAr^F₄], and the corresponding single-crystal X-ray characterisation of [Li(H₂O)][BAr^F₄], Na[BAr^F₄]˙ and K[BAr^F₄].

Grignard Reagents on a Tab: Direct Magnesium Insertion under Flow Conditions

An on-demand preparation of organomagnesium reagents is presented using a new flow protocol. The risks associated with the activation of magnesium are circumvented by a new on-column initiation procedure. Required amounts of solutions with a precise titration were obtained. Telescoped flow or batch reactions allow access to a diverse set of functional groups.

CuI promoted sulfenylation of organozinc reagents with arylsulfonyl chlorides

A CuI promoted sulfenylation of organozinc reagents with arylsulfonyl chlorides/PPh₃ has been explored.

Magnesium salt promoted tandem nucleophilic addition-Oppenauer oxidation of aldehydes with organozinc reagents

A magnesium salt promoted synthesis of ketones via tandem nucleophilic addition-Oppenauer oxidation of aldehydes using organozinc chemistry was demonstrated. Magnesium salts concomitantly generated via magnesium metal mediated organohalide zincation exhibit high efficacy for nucleophilic addition of organozinc reagents to aromatic aldehydes and thereafter Oppenauer oxidation whereby ketones are formed in high to excellent yields.

Iron-mediated inter- and intramolecular reductive cross-coupling of unactivated alkyl chlorides with aryl bromides

Efficient inter- and intramolecular reductive cross-coupling of unactivated alkyl chlorides by Fe(PPh₃)₂Cl₃.

Optimization of potency and pharmacokinetic properties of tetrahydroisoquinoline transient receptor potential melastatin 8 (TRPM8) antagonists

Transient receptor potential melastatin 8 (TRPM8) is a nonselective cation channel expressed in a subpopulation of sensory neurons in the peripheral nervous system. TRPM8 is the predominant mammalian cold temperature thermosensor and is activated by cold temperatures ranging from 8 to 25 °C and cooling compounds such as menthol or icilin. TRPM8 antagonists are being pursued as potential therapeutics for treatment of pain and bladder disorders. This manuscript outlines new developments in the SAR of a lead series of 1,2,3,4-tetrahydroisoquinoline derivatives with emphasis on strategies to improve pharmacokinetic properties and potency. Selected compounds were profiled in two TRPM8 target-specific in vivo coverage models in rats (the icilin-induced wet dog shake model and the cold pressor test). Compound 45 demonstrated robust efficacy in both pharmacodynamic models with ED90 values <3 mg/kg.

Rapid synthesis of an electron-deficient t-BuPHOX ligand: cross-coupling of aryl bromides with secondary phosphine oxides

Herein an efficient and direct copper-catalyzed coupling of oxazoline-containing aryl bromides with electron-deficient secondary phosphine oxides is reported. The resulting tertiary phosphine oxides can be reduced to prepare a range of PHOX ligands. The presented strategy is a useful alternative to known methods for constructing PHOX derivatives.

Synthesis and herbicidal activities of novel 3-N-substituted amino-6-methyl-4-(3-trifluoromethylphenyl)pyridazine derivatives

4-(3-Trifluoromethylphenyl)pyridazine is a new series of compounds with bleaching and herbicidal activities. Starting from ethyl 2-(3-trifluoromethylphenyl)acetate, an important intermediate 7 was synthesized in five steps with a moderate total yield of 51.5% in a safe and practical way. Twenty-six novel 3-N-substituted amino-6-methyl-4-(3-trifluoromethylphenyl)pyridazine derivatives were synthesized and evaluated through a Spirodela polyrrhiza test and greenhouse test. Some compounds can completely inhibit Chl at 1 microg/mL and exhibit equal or higher herbicidal activities with the commercial bleaching herbicide diflufenican against dicotyledonous plants at a rate of 75 g/ha.

Synthesis and herbicidal activity of novel alpha,alpha,alpha-trifluoro-m-tolyl pyridazinone derivatives

A series of novel alpha,alpha,alpha-trifluoro-m-tolyl pyridazinone derivatives was synthesised. Herbicidal activities of the two intermediate compounds and 15 pyridazinone derivatives were evaluated through barnyardgrass and rape cup tests and Spirodela polyrrhiza (L.) Schleiden tests. Selected compounds were also evaluated under greenhouse conditions. Bleaching activities were observed at 10 microg ml(-1) and some compounds exhibited herbicidal activities at a rate of 300 g ha(-1). The relationship between crystal structures and herbicidal activities is discussed through a comparison of two compounds (5a and 5f).

Sodium Tetrakis[(3,5-trifluoromethyl)phenyl]borate (NaBArF(24)): Safe Preparation, Standardized Purification, and Analysis of Hydration

A safe, convenient preparation of the reagent sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate (NaBArF(24)) has been devised by utilizing a magnesium-bromine exchange reaction in the absence of metallic magnesium. Purified material was then rigorously dried over P(2)O(5) (NaBArF(24) with < 500 ppm H(2)O by mass) or recrystallized as a hydrate (NaBArF(24).2.6 +/- 0.1H(2)O). Accurate analysis of the water content of these samples by (1)H NMR was accomplished by using dimethylzirconocene [Cp(2)Zr(CH(3))(2)].