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3(5)-Nitropyrazoles, such as 3,5-dmitropyrazole (2f), can be readily synthesized by thermal rearrangement of A-nitropyrazoles. In turn, 3 (5 ),4-dinitropyrazoles are obtained by further nitration of some 3(5)-nitropyrazoles.The direct nitration of pyrazole, using nitric acid or mixtures of nitric acid and sulfuric acid,4,5 leads to substitution in the 4 position, in line with the behavior of other electrophilic reagents. Moreover, no further nitration of 4-nitropyrazoles has been reported in the literature. Reports on formation of 3-nitropyrazoIes either concern compounds synthesized by other methods such as ring closure reactions4,6 or by nitration of 1,4disubstituted pyrazo!es,7,8a,b neither of which appear to be general methods for the synthesis of 3-nitropyrazoles. It is worth notice that in the latter case further nitration to 3,5-dinitropyrazoles can occur.7 Recently three different groups of workers independently reported on the synthesis of the unsubstituted 3(5)-nitropyrazole (2a). Bagal, et al.,e obtained 2a via diazotation of 3(5)-aminopyrazole, and Birkofer10 substituted the trimethylsilyl group in 3(5)-trimethylsilylpyrazole by a nitroso group, which

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Ir I -catalyzed allylic alkylations of linear aryl-substituted allylic acetates proceed with enantiomeric excess of up to 95% ee using bidentate phosphinooxazolines as chiral ligands. The chiral (π-allyl)Ir III complexes 14 and 15 have been characterized by X-ray crystal structure analysis and spectroscopic data. The stoichiometric reaction between sodium dimethyl malonate and complex 14 proceeded with nucleophilic addition at the central allylic carbon as well as ligand exchange at Ir to give the iridacyclobutane complex 16, which was fully characterized. Complex 16 was transformed into (π-allyl)Ir III complexes by treatment with Lewis acid or iodine.

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S CH diene), 14.65 µ; nmr (DMSO-dg) 4.98-5.73 (m, 3 H), 6.70-7.38 (m, 2 ), 8.02-8.41 (m, 4, aromatic); mass spectrum m/e 218 (molecular ion), 150 (as expected for loss of the fragment NHCH=CHCH=CH").