نتایج جستجو برای: bridged systems
تعداد نتایج: 1189900 فیلتر نتایج به سال:
The bis(N-heterocyclic carbene)(diphenylacetylene)palladium complex [Pd(ITMe)2(PhC≡CPh)] (ITMe=1,3,4,5-tetramethylimidazol-2-ylidene) acts as a highly active pre-catalyst in the diboration and silaboration of azobenzenes to synthesize a series of novel functionalized hydrazines. The reactions proceed using commercially available diboranes and silaboranes under mild reaction conditions.
A six-membered N-heterocyclic carbene fused with a spiro-scaffold is designed. The new NHC shows stronger σ-donation ability than typical 5-membered NHCs. This property leads to interesting reactivities of this spiro-fused six-membered NHC. For example, the NHC-BF3 Lewis pair complex can be readily prepared by using LiBF4 as the BF3 source, or through a direct bond-reconstruction of the tetrafl...
Macrocage molecules with a bridged rotor have been synthesized as molecular gyroscopes. The kinetics of the oxidation reaction of the thiophene-bridged molecular gyroscope, whose thiophene ring was bridged inside a silaalkane cage, was investigated. A remarkable kinetic stabilization against the oxidation of the thiophene moiety induced by the molecular cage framework was observed.
Both square planar and tetrahedral isomers of the four-coordinate complex [Co(Bc(tBu))2] with a bis(3-tert-butylimidazol-2-ylidene)borate ligand (Bc(tBu)) have been isolated while only a tetrahedral configuration was found for the Fe(ii) analogue [Fe(Bc(tBu))2]. Novel co-crystals containing both isomers of [Co(Bc(tBu))2] have been obtained from recrystallization.
A catalytic method has been developed for construction of indoline-2-thiones containing an all-carbon quaternary centre at the C-3 position. Successive treatment of α,β-unsaturated aldehydes bearing an isothiocyanato moiety with an in situ generated N-heterocyclic carbene and an appropriate heteroatomic nucleophile provided the 3,3-disubstituted indoline derivatives in moderate to good yields.
This review presents examples from the chemical literature of syntheses of bridged-polycyclic products via C-H bond insertion by carbenes and nitrenes. Applications to natural product synthesis, a description of the essential elements in substrate-controlled reactions, and mechanistic details of transformations are presented. Overall, these transformations allow the construction of important ri...
The combination of aminocatalysis with N-heterocyclic carbene catalysis has been extended to a switchable dual catalytic system, which allowed a direct enantioselective entry to bridged bicyclo[3.n.1] ring systems and the total synthesis of the natural product (1R)-suberosanone.
Highly functionalized dihydropyridinones were synthesized via the N-heterocyclic carbene-catalyzed enantioselective [4 + 2] annulation of α-chloroaldehydes and azadienes. Hydrogenation of the resulted dihydropyridinones afforded the corresponding piperidinones with high enantiopurity.
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