Charlotte Jane Mitchell

Mild C-H Halogenation of Anilides and the Isolation of an Unusual Palladium(I)-Palladium(II) Species

Eine einfache Pd-katalysierte ortho-selektive Bromierung und Chlorierung von Aniliden gelingt unter aeroben Bedingungen bei Raumtemperatur, wenn N-Halogensuccinimide (NXS) in Gegenwart von p-Toluolsulfonsaure (PTSA) eingesetzt werden. Der orthopalladierte PTSA-Komplex ist nicht nur katalytisch aktiv, sondern geht auch einen reduktiven Prozess unter Bildung eines ungewohnlichen PdI-PdII-Tetramers ein (siehe Struktur; Pd grun, O rot, S gelb, C grau).

Solvent free catalytic C-H functionalisation.

Solvent-free reaction conditions facilitate a range of aromatic C-H functionalisations that traditionally require acidic or disfavoured solvents. These reactions include selective ortho- and meta-arylation of aryl carbamates and anilides and selective halogenation reactions.

Pyrazolopyridines as a novel structural class of potent and selective PDE4 inhibitors.

Optimisation of a high-throughput screening hit resulted in the discovery of 4-(substituted amino)-1-alkyl-pyrazolo[3,4-b]pyridine-5-carboxamides as potent and selective inhibitors of Phosphodiesterase 4 (PDE4). Herein, we describe early SAR studies around this novel template highlighting preferred substituents and rationalization of SAR through X-ray crystal structures of analogues bound to the PDE4 active site. Pyrazolopyridine 20a was found to be a potent and selective PDE4 inhibitor which also inhibits LPS induced TNF-alpha production from isolated human peripheral blood mononuclear cells and has an encouraging rat PK profile suitable for oral dosing.

Solvent-free aromatic C–H functionalisation/halogenation reactions

The solvent-free, palladium-catalysed reaction of anilides with CuCl(2) in the presence or absence of copper acetate yields ortho-chlorinated anilides in good to excellent yields, even on a large scale (100 mmol). By contrast, the equivalent reactions with copper bromide, either solvent free or in 1,2-dichloroethane, in the presence or absence of palladium, under air or inert conditions, gave the products of simple electrophilic bromination. Mechanistic studies highlighted the involvement of palladacyclic intermediates, one of which was characterised crystallographically, which undergo subsequent reaction with copper(II) chloride to yield the chlorinated anilide products.

Pyrazolopyridines as potent PDE4B inhibitors: 5-heterocycle SAR.

Following the discovery of 4-(substituted amino)-1-alkyl-pyrazolo[3,4-b]pyridine-5-carboxamides as potent and selective phosphodiesterase 4B inhibitors, [Hamblin, J. N.; Angell, T.; Ballentine, S., et al. Bioorg. Med. Chem. Lett.2008, 18, 4237] the SAR of the 5-position was investigated further. A range of substituted heterocycles showed good potencies against PDE4. Optimisation using X-ray crystallography and computational modelling led to the discovery of 16, with sub-nM inhibition of LPS-induced TNF-α production from isolated human peripheral blood mononuclear cells.