10.1039/b411111g
The research focuses on the development of a simple solid phase diversity linker strategy using enol phosphonates for combinatorial chemistry. The main objective was to create stable, storable polymer-bound lactam enol phosphonates on polystyrene resin, which could be released using Suzuki cross-coupling conditions to yield 2-arylenamides. The experiments involved the synthesis of enol phosphonates by reacting phenol with phenylphosphonic dichloride in the presence of a base, followed by combination with p-cresol to form the desired phenyl phosphonate. The study explored the stability and reactivity of these compounds in cross-coupling reactions and attempted to address issues related to homo-coupling of boronic acids. The analyses used included 31P NMR spectroscopy to confirm the presence of phosphonate on the resin and to monitor the progress of the reactions. The yields of the final products were determined after purification and isolation, with the results indicating moderate to good overall yields for the 2-arylenamides.
10.1002/chem.201101266
The study presents the design, synthesis, and characterization of a tetrathiafulvalene-calix[4]pyrrole receptor, which can be controlled by external acid/base inputs to regulate its molecular recognition of guest molecules. The receptor, named ouroboros due to its self-complexation property, is composed of three identical tetrathiafulvalene (TTF) units and a fourth TTF unit appended with a phenol moiety. The phenol group allows for the receptor to switch between a locked (ouroboros) and unlocked state through deprotonation/protonation, thereby controlling the binding and release of guest molecules like 1,3,5-trinitrobenzene (TNB). The chemicals used in the study include tetrathiafulvalene derivatives, phenol, and various reagents for synthesis such as CsOH·H2O, 4-(3-bromopropyl)phenol, NaOMe, and tetrabutylammonium chloride (TBACl). These chemicals served the purpose of constructing and modifying the receptor molecule, as well as studying its interactions with TNB guests through absorption and 1H NMR spectroscopy, which revealed the receptor's ability to switch conformations and control guest binding based on pH changes.
10.1007/s11172-010-0175-3
The research focuses on a novel method for the thiomethylation of phenols, which are considered promising as antioxidants and bioantioxidants. The study aims to improve upon existing synthesis methods that typically involve intermediate products containing a methylene fragment in the phenol molecule, which are often slow and require harsh conditions. The researchers introduce alkyl diethylaminomethyl sulfides as efficient reagents for introducing alkylthiomethyl groups into phenols, demonstrating high conversion rates and yields. Key chemicals used in the process include diethylaminomethyl dodecyl sulfide (1a), diethylaminomethyl octadecyl sulfide (1b), 2,6-dimethylphenol, p-cresol, and phenol. The conclusions drawn from the study highlight the simplicity and efficiency of the proposed method, which selectively produces mono- and disubstitution products with a preference for ortho-substitution under the tested conditions, and suggest that the reagents used are promising for further testing with other nucleophiles.
10.1021/jm00174a020
The research focuses on the structure-activity relationship of antiestrogens, specifically phenolic analogues of 2,3-diaryl-2H-1-benzopyrans (DABP). The purpose of the study was to synthesize and evaluate these compounds for their potential as antiestrogens, with the aim of understanding the molecular origins of their partial agonist-antagonist character. The conclusions drawn from the research indicated that the incorporation of hydroxyl groups at certain positions in the benzopyran structure significantly improved receptor affinity and antagonist activity without affecting estrogen agonist activity. Notably, the monophenol 19 and the diphenol 25 emerged as potent antiestrogens, exhibiting marked antiestrogenic activity and being more effective than tamoxifen, trioxifen, and LY-117018.
10.1021/ic401747n
The study investigates the synthesis, structure, and catalytic performance of new ytterbium(II) and ytterbium(III) complexes supported by [ONOO]-type amine bis(phenolate) ligands in the ring-opening polymerization (ROP) of rac-lactide. The researchers synthesized two Yb(II) complexes (1 and 2) and two Yb(III) complexes (4 and 5) using various ligand precursors and ytterbium sources. Complexes 1 and 2 were prepared by an amine elimination reaction of Yb(II)(N(SiMe3)2)2(TMEDA) with ligand precursors, while complexes 4 and 5 were synthesized through a double protonation reaction of Yb(III)(C5H5)3THF with ligand precursors and phenols. The structures of these complexes were determined using X-ray crystallography. In the ROP of rac-lactide, complexes 1 and 4 exhibited high activity and stereoselectivity, producing heterotactic polylactide with narrow molar mass distributions and high probability of racemic enchainment (Pr values of 0.97-0.99). Complex 5 showed less controlled polymerization. The study highlights the importance of the ligand framework in determining the activity and stereoselectivity of the ytterbium complexes for rac-lactide polymerization.
10.1080/10426500902930159
The research focuses on the interaction of bis(chloromethyl) isocyanatophosphinate with chiral α-aminoalkylphosphonates, leading to the stereoselective synthesis of 2,4-dioxo-5-phenyl-1-phenylethylamino-4-phenoxy-1,3,4-diazaphospholidine. The study involves the synthesis of O,O-diphenyl-(α-phenylethylamino)benzylphosphonate in both racemic and enantiopure forms, which then reacts with bis(chloromethyl)isocyanatophosphinate to form the target diazaphospholidine. Sodium phenolate was used as a catalyst in the synthesis of compound 6A (enantiopure form). Phenol was Involved in the cyclization step of the reaction to form the final diazaphospholidine product. The experiments utilized various analytical techniques, including IR spectroscopy, NMR spectroscopy (1H, 13C, and 31P), mass spectrometry, and X-ray single crystal diffraction to characterize the reactants and products. The research also explores the stereoselectivity of the reaction by using enantiopure aminophosphonates, aiming to produce enantiopure phosphorus-nitrogen containing heterocycles, which are of interest due to their potential applications in pharmaceuticals and agrochemicals.
10.1021/jacs.7b04813
The research focuses on the chemoselective asymmetric intramolecular dearomatization of phenols using silver phosphate-catalyzed α-diazoacetamides. The study explores the unique reactivity of silver carbenoids, which preferentially promote dearomatization over other reactions like C–H insertion and Büchner reaction, typically catalyzed by Rh or Cu. Through experimental and computational analysis, the researchers demonstrate that silver carbenoids exhibit carbocation-like character, leading to highly enantioselective transformations. The reaction conditions were optimized using various catalysts, additives, and solvents, with benzoic acid being identified as a particularly effective additive. The substrate scope was also investigated, revealing that the method is broadly applicable to phenols with ortho-substituents, and the research provides a facile access to chiral spirolactams with all-carbon quaternary stereogenic centers. The study utilized a range of analytical techniques, including H-NMR analysis for product determination and Mosher’s ester analysis for absolute configuration determination. Computational studies involved DFT calculations to elucidate the chemoselectivity and reaction mechanisms, with a focus on the LUMO maps of Rh and Ag carbenoids.
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