A Nitrogen-Assisted One-Pot Heteroaryl Ketone Synthesis from Carboxylic Acids and Heteroaryl Halides.

A practical and highly effective one-pot synthesis of versatile heteroaryl ketones directly from carboxylic acids and heteroaryl halides under mild conditions is reported. This method does not require derivatization of carboxylic acids (preparation of acid chlorides, Weinreb amides, etc.) or the use of any additives/catalysts. A wide substrate scope of carboxylic acids with high functional group tolerance has also been demonstrated. The results reveal that the presence of an α-nitrogen on the halide substrate greatly improves the desired ketone formation.

Regiospecificity in the Exchange Coupling of the Spins of Copper(II) Ion Coordinated with the Ring Nitrogen Atoms and N-tert-Butylaminoxyl Radical Attached as a Substituent on the Pyridine and N-Phenylimidazole Rings.

Complexes of bis(hexafluoroacetylacetonato)copper(II) [Cu(hfac)(2)] ligated with 3- and 4-(N-oxyl-tert-butylamino)pyridines (3NOPy and 4NOPy) and N-{3- and 4-(N-oxyl-tert-butylamino)phenyl}imidazoles (3NOIm and 4NOIm) were prepared. The 1:2 complexes [Cu(hfac)(2)(3NOPy and 4NOPy)(2)] have hexacoordinated octahedral structures in which the two pyridyl nitrogen atoms are coordinated to the copper(II) ions in the trans configuration. The 1:1 complex [Cu(hfac)(2)(4NOPy)] has a distorted pentacoordinated pseudo-head-to-tail cyclic dimer structure in which the oxygen atom of the aminoxyl group of one complex is situated at a distance of 2.79 Å from the copper ion of the other complex. The magnetic properties of these and two other complexes, [Cu(hfac)(2)(3NOIm and 4NOIm)(2)], were investigated using a SQUID susceptometer. Temperature dependence studies of the chi(mol)Tvalues of [Cu(hfac)(2)(4NOPy)(2)] revealed that the two aminoxyl radicals interact ferromagnetically with the copper(II) ion (S = (1)/(2)) with an exchange parameter J/k(B) = 60.4 +/- 3.3 K to produce a quartet ground state (S = (3)/(2)). On the other hand, the chi(mol)T value of the isomeric [Cu(hfac)(2)(3NOPy)(2)] was nearly constant at 0.5 emu K mol(-)(1) in the temperature range 5-300 K. A rectangular four-spin model was fitted to the chi(mol)T vs T plot for complex [Cu(hfac)(2)(4NOPy)] to give J/k(B) = 58.6 and 58.5 K. Similarly, the J values for [Cu(hfac)(2)(3NOIm and 4NOIm)(2)] were negative and positive, respectively, but their absolute J values were too small to determine in both cases.