Refernces
10.1002/ejoc.200800529
The research focuses on the zinc homologation-elimination reaction of α-sulfinyl carbanions as a novel synthetic route to olefins. The study explores the reaction of α-lithiosulfinyl carbanions with zinc carbenoids, which can proceed either intermolecularly through an SN2-type process involving transmetalation into an organocopper derivative or intramolecularly via higher-order zincates through a tandem zinc homologation-β-elimination sequence. The experiments utilize various alkyl sulfoxides as starting materials, which upon treatment with lithium diisopropylamide (LDA) at low temperatures, are transmetalated to form α-sulfinyl copper species. These are then reacted with zinc carbenoids to yield olefins through a β-elimination reaction. The research also investigates the use of DMSO as a source of terminal olefins and explores the intramolecular 1,2-zincate rearrangement as a method to improve the reaction methodology. N,N,N',N'-Tetramethylethylenediamine (TMEDA) and n-BuLi for generating higher-order zincates. The analyses used to characterize the products include NMR spectroscopy, which is detailed in the results section for various synthesized olefins.
10.1039/c8nj01975d
The research focuses on the exploitation of the dual reactivity of Weinreb amide to synthesize a variety of symmetrical and dissymmetrical 2,5-disubstituted pyrrolidines from readily available starting materials. The experiments involve a sequential microwave-assisted tandem double cross-metathesis/ring-closing double aza-Michael (CM/RCDAM) approach to create a Weinreb-based pyrrolidine platform, which is then subjected to late-stage functionalization using a diverse range of organolithium and Grignard reagents. The reaction selectivity is controlled by balancing the steric encumbrance of the reaction partners, the basicity of the organometallic species, and the liganding ability of the pyrrolidine nitrogen atom. External competitive ligands, such as TMEDA, were also used to reverse chemoselectivity. Analyses included NMR, HRMS, and IR spectroscopy to characterize the synthesized compounds, demonstrating the successful application of this strategy in generating molecular diversity for potential drug discovery applications.
10.14233/ajchem.2014.16244
The study focuses on the development of a novel catalytic enantioselective method for the synthesis of chiral organoboronates, which are valuable precursors for the preparation of enantio-enriched compounds. The researchers synthesized a novel compound, 1-[2-{(1R,2S)-2-(chloromethyl)cyclopropyl]ethyl}-4-methoxybenzene, through a cyclopropanation reaction using boronate complexes as nucleophiles. Key chemicals used in the study include N,N-diisopropylcarbamoyl chloride, 3-(4-methoxyphenyl)-1-propanol, n-butyl lithium (n-BuLi), allylboronic acid pinacol ester, (-) sparteine, N,N,N,N-tetramethyl-ethylenediamine (TMEDA), 1,3-bis(trifluoromethyl)-5-bromobenzene, N-chlorosuccinimide (NCS), and trichloroisocyanuric acid (TCCA). These chemicals served various purposes, such as reactants, catalysts, and reagents in the synthesis process, with the aim of achieving high yields and enantioselectivity in the production of the target chiral compound. The study also investigated the effects of temperature and the choice of aryllithiums and electrophiles on the yields and stereoselectivity of the reaction.
10.1002/ejoc.201001061
The research investigates the impact of solvents and additives on the steric course of the [2,3]-Wittig rearrangement of chiral 1,3-diphenyl-1-propenyloxy-2-propen-1-yl carbanion and its derivatives. The purpose of the study was to understand how the configurational stability of chiral carbanions is influenced by solvents and additives, which is crucial for maintaining the optical purity of chiral centers during chemical reactions. The researchers concluded that the steric course of the rearrangement is significantly affected by the solvent and additive used, with the configurational stability of chiral carbanions being dependent on the solvent, reflecting the ratio of contact ion pairs (CIP) and separated ion pairs (SIP) associated with their solvated structures. Key chemicals used in the process include nBuLi, LDA, KHMDS, tetramethylethylenediamine (TMEDA), Me2NEt, hexamethylphosphoramide (HMPA), and various solvents such as Et2O, CPME, MTBE, DME, THF, and 1,4-dioxane. The study also utilized a range of substrates, including (S)-6a–g, which bear either an inductively anion-stabilizing halogen atom or a cyano group at the meta- or para-positions.
10.1021/acs.joc.0c00263
This research aimed to develop a new heterocyclic system with potential applications in materials science and pharmaceuticals. The authors synthesized 2H-bis([1,2,3]triazolo)[5,1-a:4',5'-c]isoquinolines using a three-step process involving readily available aryl hydrazines and o-alkynylbenzaldehydes. The key chemicals included sodium azide, copper(I) chloride (CuCl), and tetramethylethylenediamine (TMEDA). The synthesized compounds exhibited high quantum yields of fluorescence (up to 98%) and significant Stokes shifts (up to 67 nm), making them attractive blue-emitting fluorophores. The study concluded that these heterocycles could be valuable for creating new dyes and OLED materials due to their efficient blue fluorescence and structural diversity.
10.1021/om4006609
The study focuses on the synthesis, structural diversity, and catalytic activity of five dilithium compounds containing bidentate dianionic pyrrolyl ligands, namely compounds 1-5. These compounds were prepared by reacting various aminopyrrolyl ligand precursors with two equivalents of nBuLi in the presence of TMEDA (N,N,N',N'-tetramethylethylenediamine) in hexane. The synthesized compounds were characterized by their structural features and tested for their efficiency as catalysts in the amidation reactions of aldehydes with amines. The study found that these dilithium compounds, particularly compound 3, served as effective catalysts for the amidation reactions under mild conditions, leading to the formation of amides in good to excellent yields. The purpose of these chemicals was to explore their potential as catalysts in organic reactions, specifically in the synthesis of amides from aldehydes and amines, which is an important transformation in organic chemistry with applications in the pharmaceutical and chemical industries.
10.1055/s-1997-982
The study investigates the catalytic asymmetric reduction of various ketones using transient hypervalent silicon hydrides derived from trialkoxysilanes. The trialkoxysilanes, upon activation by a small amount of a chiral nucleophile, react with the carbonyl group of ketones to form silyl-protected alcohols, which are then cleaved to yield enantiomerically enriched alcohols. The researchers conducted a screening of reaction parameters and found that the use of certain chiral catalysts, such as the monolithio salts of (R)-binol and its derivatives, in combination with solvents like ether and additives like TMEDA, significantly enhanced both the yield and enantioselectivity of the reductions. The study demonstrated that steric effects around the carbonyl group of the ketones played a crucial role in determining the enantioselectivity of the products.
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