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51.
Iwai S Kabata T Maeda T Kajino Y Ogawa K Kuroda K Tsuchiya H 《Modern rheumatology / the Japan Rheumatism Association》2012,22(5):766-768
We report the case of a 57-year-old woman with hyperostosis around the bilateral acetabulum associated with untreated secondary hypoparathyroidism. She presented with gait disturbance and inability to walk. Radiographs showed abnormal ossification around her hips. We resected the ossifications to improve joint function. One year after surgery, radiographs showed no recurrence of ossification. When radiographs show excessive hyperostosis, it is important to exclude presence of metabolic bone disease. 相似文献
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A new synthetic method is described to construct 1,2,4-azadiphosphole derivatives based on vanadium-catalyzed [2+2+1] cycloaddition reactions. Reactions of azobenzenes as nitrogen sources with phosphaalkynes as phosphorous counterparts in the presence of VCl2(thf)2 as a catalyst afford the corresponding 1,2,4-azadiphospholes.Vanadium-catalyzed [2+2+1] cycloaddition reactions opened a new access to phosphorous-heterocycles.Phosphorus heterocycles have provided important structural motifs to explore materials science and coordination chemistry.1 To access diverse skeletons, development of new and efficient synthetic methods is quite important. In addition to the conventional synthetic methods typically forming carbon–phosphorous single bonds, the use of phosphaalkynes as substrates is beneficial to construct phosphorous-containing π-systems.2 Stoichiometric reactivity of phosphaalkynes with transition metal complexes has been studied extensively,3 but catalytic reactions of phosphaalkynes under transition metal catalysis have been limited to several sporadic examples.4,5 Recently, our group has reported catalytic [2+2+2] cycloaddition reactions to produce phosphabenzenes and [3+2] cycloaddition reactions to produce 1,3-azaphospholes based on the use of phosphaalkynes as substrates.5 To investigate further utility of phosphaalkynes to prepare aromatic compounds containing phosphorus atoms, we have focused on the synthesis of 1,2,4-azadiphospholes as next targets.Synthetic examples of 1,2,4-azadiphospholes have been limited to only a few reports.6,7 To the best of our knowledge, the first synthesis of the 1,2,4-azadiphosphole skeleton was reported in 1991, where a 1,2,4-azadiphosphole derivative was prepared based on a thermal dimerization of an amino-substituted phosphaalkyne.6a Later, other groups reported stoichiometric reactions of titanium- and vanadium-imide complexes as nitrogen sources with phosphaalkynes.6b–d Although these stoichiometric reactions provided effective synthetic methods of 1,2,4-azadiphospholes, transition metal-catalyzed synthesis of 1,2,4-azadiphospholes has never been achieved until now.Recently, titanium-catalyzed [2+2+1] cycloaddition reactions have been reported by Tonks and co-workers to prepare pyrroles from reactions of azobenzenes with alkynes (Scheme 1a).8 In this reaction system, titanium-imide species generated from azobenzenes worked as a key intermediate. More recently, a similar pyrrole synthesis using vanadium-catalyzed reaction system has been reported by Tonks, Mashima, Tsurugi and co-workers.9Open in a separate windowScheme 1Catalytic [2+2+1] cycloaddition reactions with azobenzenes as nitrogen sources in heterocycle synthesis.Based on the research background, we have envisaged metal-catalyzed [2+2+1] cycloaddition reactions of azobenzenes with phosphaalkynes to produce 1,2,4-azadiphospholes (Scheme 1b). As a result, we have found that some vanadium complexes worked as effective catalysts toward the formation of 1,2,4-azadiphospholes. Herein, we report experimental results in detail.First, investigation of reaction conditions was carried out with the use of azobenzene (1a) and 1-adamantylphosphaethyne (2a) as typical substrates. When the reaction of 1a (1 equiv.) with 2a (2 equiv.) in the presence of 20 mol% of VCl3(thf)3 was carried out in toluene at 110 °C for 16 hours, the desired 1,2,4-azadiphosphole (3a) was obtained in 48% yield ( Entry [V] catalyst Ligand Yield (%) 1 VCl3(thf)3 — 48 2 VBr3(thf)3 — 42 3 VCl3(py)3 — 0 4 VCl2(thf)2 — 60 5 VCl2(1,4-dioxane)2 — 47 6 VI2(thf)4 — 27 7 VCl2(thf)2 dppm 27 8 VCl2(thf)2 dppe 20 9 VCl2(thf)2 2,2′-Bipyridine 0