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71.
72.
Kitagawa O Takahashi M Yoshikawa M Taguchi T 《Journal of the American Chemical Society》2005,127(11):3676-3677
In the presence of (R)-DTBM-SEGPHOS-Pd(OAc)2 catalyst, N-arylation of ortho-tert-butyl-NH-anilides with 4-nitroiodobenzene proceeds with high enantioselectivity (89-95% ee) to give optically active atropisomeric anilides possessing N-C chiral axis. Furthermore, the intramolecular version of the present catalytic asymmetric N-arylation gave atropisomeric lactams with high optical purity (94-96% ee). 相似文献
73.
74.
Sasada T Aoki Y Ikeda R Sakai N Konakahara T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(34):9385-9394
The [5+1] annulation of enamidines, which were prepared from functionalized silanes, organolithium compounds and two nitriles, with N,N-dimethylformamide dialkyl acetals as the C1 unit is described, leading to the synthesis of tri- and tetrasubstituted pyrimidine derivatives under catalyst- and solvent-free reaction conditions. Furthermore, the [5+1] annulation of enamidines by using orthoesters as the C1 unit is described, in which catalytic amounts of ZnBr(2) catalyze the annulation to produce polysubstituted pyrimidines under toluene or xylene reflux conditions. Moreover, the combination of a reductive ring-opening reaction with [Mo(CO)(6)] and a subsequent intramolecular cyclization with tBuOK effectively causes a skeletal transformation from the pyrimidines containing an isoxazolyl and an ethoxy substituent to form pyrido[2,3-d]pyrimidin-5-one frameworks in excellent yield. 相似文献
75.
76.
Takeo Iida Motoharu Nakanishi Kunio Got
《Journal of polymer science. Part A, Polymer chemistry》1974,12(4):737-749
Poly(vinyl chloride) (PVC) alone or mixed with 10 wt-% and 50 wt-% TiO2, SnO2, ZnO, and Al2O3 were pyrolyzed by using a pyrolysis gas chromatograph. Benzene, toluene, ethylbenzene, o-xylene, styrene, naphthalene, and various chlorobenzenes were identified. No hydrocarbons could be detected in pyrolysis products of any samples at 200°C. More aromatic hydrocarbons than aliphatic hydrocarbons are released from the PVC–TiO2 system and in preheated PVC. The contrary result is observed in the PVC–ZnO and PVC–SnO2 systems. Aromatics having methyl endgroups are easily released from the PVC–ZnO and PVC–SnO2 systems and at elevated pyrolysis temperature, because methylene groups are easily isolated along the chain by ZnO, SnO2 and the heating. The release of ethylbenzene o-xylene, and chlorobenzenes suggests a repeated dehydrochlorination and recombination of HCl and Cl2 to double bonds along the chain. Possible decomposition mechanisms of PVC are discussed. 相似文献
77.
78.
Physics of the Solid State - Transition metal doped cesium lead halide (CsPbI3) perovskite compounds were studied for application in photovoltaic solar cells. Electronic structures, chemical shifts... 相似文献
79.
Yoshihiko Ito Hiroshi Imai Takaharu Matsuura Takeo Saegusa 《Tetrahedron letters》1984,25(29):3091-3094
This paper describes the finding that BF3 etherate effectuates the conjugate additions of copper(I) aldimines, generated in situ from lithium aldimines and Cu(I) halide, to α,β-unsaturated carbonyl compounds to produce 4-(N-alkylimino)-ketones, which give on acid hydrolysis 1,4-diketone derivatives. 相似文献
80.
N-(omega-Bromoalkyl)-amino acid derivatives, readily prepared from natural alpha-amino acids, gave cyclic amino acids with a quaternary stereocenter by treatment with potassium hexamethyldisilazaide in DMF. The chirality of parent amino acids was almost completely preserved during an enolate-formation and cyclization process, giving aza-cyclic amino acids in up to 98% ee in retention of configuration. This method is applicable to the asymmetric synthesis of azetidine, pyrrolidine, piperidine, and azepane derivatives. The asymmetric cyclization seems to proceed via an axially chiral enolate intermediate and not through a concerted SEi process. 相似文献