Refernces
10.1021/ja076797c
The study presents a novel catalytic asymmetric cyclopropanation reaction of enones using dimethyloxosulfonium methylide, promoted by a La-Li3-(biphenyldiolate)3 + NaI complex. The reaction showcases high enantioselectivity, with up to 99% ee, and is applicable to a variety of enones, including those with electron-withdrawing or electron-donating substituents and heteroaryl-substituted enones. The use of NaI as an additive, along with biphenyldiol as a ligand, is crucial for achieving this level of selectivity. The reaction conditions were optimized to allow for slow addition of enones, which further improved the enantioselectivity. The study also explores the potential of the catalyst system with other substrates, such as an N-acylpyrrole, and discusses the role of NaI in the reaction mechanism, suggesting a partial alkali metal exchange occurs in situ to form a La-Li2-Na-(biphenyldiolate)3 complex. The findings provide a complementary approach to existing methods for catalytic asymmetric cyclopropanation and highlight the importance of the mixed-alkali metal system in achieving high yields and enantioselectivity.
10.1021/om034385g
The study investigates the reactions of 3-(pentafluorophenyl)indene and (pentafluorophenyl)cyclopentadiene with tetrakis(dimethylamido)titanium(IV), resulting in the formation of products where one or both ortho fluorines of the C6F5 group are replaced by dimethylamino groups. This suggests a titanium-mediated, intramolecular nucleophilic aromatic substitution mechanism. The research led to the isolation of organic products and the conversion of substituted cyclopentadiene to a ferrocene derivative. The study provides insights into the selective activation of polyfluorinated organic compounds, a significant challenge in synthetic chemistry, and contributes to the understanding of transition metal complex mechanisms for C-F activation.
10.1021/ic702500n
The research focuses on the synthesis and characterization of a novel tetranuclear copper assembly, {N3P3Ph2[N(Me)NdCHC6H4-2-O]4Cu2}2, which contains an impressive 15 contiguous inorganic rings. The purpose of this study was to demonstrate the feasibility of modifying cyclophosphazene ligands into more complex coordinating systems, and the process involved the reaction of cyclophosphazene hydrazide with o-hydroxybenzaldehyde to form a multisite coordination ligand, which then reacted with copper(II) salts to form the tetranuclear copper assembly. The chemicals used in this process included gem-N3P3Ph2[N(Me)NH2]4 (LH4), o-hydroxybenzaldehyde, copper(II) salts such as CuCl2, and other reagents like sodium hydride and anhydrous CuCl2. The conclusions drawn from the research were that the modification of cyclophosphazene ligands into more elaborate and complex coordinating systems is indeed feasible, and this approach can significantly enhance the versatility and diversity of cyclophosphazene-based ligands, as evidenced by the successful synthesis of the polycyclic tetranuclear copper(II) assembly.
10.1016/0040-4039(91)80677-X
The research aims to develop a new method for converting dicarbonyl compounds into alkenes, specifically focusing on the synthesis of phenanthrenes from 2-(2-formylphenyl)benzaldehydes. The study explores various routes to achieve this transformation, including heating the dilithium or disodium salts of the bistosylhydrazones derived from the aldehydes. The researchers initially attempted methods such as the Bacon procedure and titanium coupling but faced challenges, especially with steric hindrance in the synthesis of 4,5-dimethoxyphenanthrene. They then explored the formation of bis-diazoalkanes from bistosylhydrazones, which upon heating, could cyclize to form phenanthrenes. Tosylhydrazine is used as a key reagent to convert the 2-(2-formylphenyl)benzaldehydes into their corresponding bistosylhydrazones. Sodium hydride (NaH) is employed to deprotonate the bistosylhydrazones, forming their sodium salts. The study concludes that this new method is effective for the preparation of sterically hindered phenanthrenes and represents a significant advancement in the field of alkene formation from dicarbonyl compounds.
10.1016/j.tet.2008.08.057
The study presents a practical and efficient one-step synthesis of (E)-β-aryl-α,β-unsaturated amides using α-sulfonyl acetamide and benzyl bromide derivatives. α-Sulfonyl acetamide acts as a key starting material, reacting with various benzyl bromides in the presence of sodium hydride to form the desired unsaturated amides with high stereoselectivity and yields. The scope of the reaction is broad for benzyl bromides with electron-withdrawing substituents on the benzene ring. The study also demonstrates the application of this method in the formal synthesis of the calcimimetic (D)-NPS R-568 and the synthesis of N,N-disubstituted (E)-acrylamides, showcasing its potential for synthesizing important compounds with biological and medicinal relevance.
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