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Janka M He W Frontier AJ Eisenberg R 《Journal of the American Chemical Society》2004,126(22):6864-6865
The dicationic Ir(III) complex [IrMe(CO)(dppe)(DIB)](BARF)2 having adjacent labile sites has been found to be a very effective catalyst for promoting the Nazarov cyclization of aryl vinyl and divinyl ketones. Spectroscopic evidence for a substate-catalyst complex before cyclization is presented. The efficiency of the cyclization is attributed to the electrophilicity of the Ir(III) complex and substrate activation via chelation. 相似文献
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I. Brissaud A. de Château-Thierry J. P. Frontier G. Lagarde 《Journal of Radioanalytical and Nuclear Chemistry》1986,102(1):131-141
Geological standards are analyzed using PIXE and PIGE techniques. The concentrations of up to 26 elements are determined and compared with those obtained by other methods. PIXE and PIGE techniques are also applied to different volcanic rock samples. Their sensitivity, accuracy, and speed of data collection and reduction, are of great interest in the study of volcanic phenomena. 相似文献
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Vaidya T Manbeck GF Chen S Frontier AJ Eisenberg R 《Journal of the American Chemical Society》2011,133(10):3300-3303
In contrast to 2-substituted pyrrole enones, furyl and benzofuryl enones do not undergo the Nazarov electrocyclization. Instead, these furyl and benzofuryl enones exhibit unusual rearrangement sequences in the presence of catalytic amounts of [IrBr(CO)(DIM)((R)-(+)-BINAP)](SbF(6))(2) (1; DIM = diethylisopropylidene malonate) and AgSbF(6) (1:1). A 1,2-H shift followed by intramolecular Friedel-Crafts alkylation leads to synthetically valuable cyclohexanones with furanylic quaternary centers. The electrophilicity of 1 is essential for this rearrangement. 相似文献
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CM Silva MF Duarte ML Mira MH Florêncio K Versluis AJ Heck 《Rapid communications in mass spectrometry : RCM》1999,13(12):1098-1103
Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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Janka M He W Haedicke IE Fronczek FR Frontier AJ Eisenberg R 《Journal of the American Chemical Society》2006,128(16):5312-5313
The first examples of a tandem Nazarov cyclization/Michael addition process are described. The sequence is efficiently catalyzed by Ir[Me(CO)(dppe)(DIB)]2+ and occurs with high diastereoselectivity, creating three contiguous stereocenters. The mechanistic factors controlling the reactivity and diastereoselectivity are discussed. 相似文献