10.1021/ol902203t
The research focuses on the synthesis of a novel C3 symmetric building block, a s-triazine-based molecule with three phosphonate groups, which can be easily synthesized in two steps starting from p-bromomethylbenzonitrile. This new building block readily undergoes olefination reactions to yield derivatives such as tris(tetrathiafulvalene)- and tris(ferrocene)-1,3,5-triazines. The experiments involved the preparation of intermediate building block 3 through reactions with triflic anhydride and trimethyl phosphite, followed by olefination reactions with formylferrocene and formylTTF to synthesize the final compounds 5 and 7. The reactants included p-bromomethylbenzonitrile, triflic anhydride, trimethyl phosphite, formylferrocene, and formylTTF. The analyses used to characterize the compounds were spectroscopic techniques (UV-vis, FT-IR, 1H and 13C NMR, HR-MS), cyclic voltammetry for electrochemical characterization, and solvatochromic studies to assess the charge-transfer properties of the synthesized molecules.
10.1021/jo026757l
The study presents three novel methods for the synthesis of 2-amido substituted furans, which are valuable intermediates in the synthesis of various natural products and alkaloids. The first method involves the thermolysis of furan-2-carbonyl azide, leading to a Curtius rearrangement and the formation of a furanyl isocyanate intermediate, which is then trapped with different organometallic reagents. The second method is a C-N cross-coupling reaction of bromo-substituted furans with amides, carbamates, and lactams, catalyzed by CuI, yielding 2- and 3-substituted amidofurans in high yields. The third method involves the reaction of cyclic carbinol amides with triflic anhydride to produce R-(trifluoromethyl)sulfonamido-substituted furans under mild conditions. These methods serve to provide diverse and efficient pathways to synthesize 2-amido substituted furans, expanding the synthetic toolkit for the preparation of complex oxygenated polycyclic compounds and potentially facilitating the synthesis of alkaloids.
10.1021/jm020335m
The study investigates a series of nonsteroidal selective glucocorticoid modulators, focusing on the effects of C-10 substitution on receptor selectivity and functional potency of 5-allyl-2,5-dihydro-2,2,4-trimethyl-1H-[1]benzopyrano[3,4-f]quinolines. The researchers synthesized various analogues with different substituents at the C-10 position, including linear two-atom appendages such as OCH3, OCF2H, NHMe, SMe, and CH2OH, to evaluate their binding affinity for the human glucocorticoid receptor (hGR) and their anti-inflammatory effects. Key chemicals used in the study included dexamethasone and prednisolone as reference glucocorticoids, along with various synthetic intermediates and reagents like DIBAL-H for reduction reactions, trifluoromethanesulfonic anhydride for sulfonylation, and cesium carbonate for alkylation. These chemicals facilitated the preparation of the target compounds and allowed for the assessment of their biological activity in receptor binding and functional assays.
10.1016/S0040-4039(00)96614-0
The research focuses on the synthesis of chiral oxetanes from sugar lactones, with the aim of creating derivatives of 3,5-anhydro-1,2-O-isopropylidene-α-D-glucuronic acid and 3,5-anhydro-1,2-O-isopropylidene-S-L-iduronic acid. The purpose of this study was to explore the ring contraction reactions of triflates of α-hydroxy-T-lactones, which provide an approach to synthesizing chiral polyfunctionalized oxetanes from sugars. The researchers used various chemicals in their process, including 1,2-O-isopropylidene-5-O-trifluoromethanesulphonyl-α-D-glucuronolactone (1), benzylamine, potassium carbonate, triflic anhydride, sodium azide, and lithium aluminum hydride. The conclusions drawn from the research indicate that the oxetane system is chemically and configurationally stable under the reaction conditions used, with no epimerization observed. The study suggests that the ring contraction of the glucuronolactone triflate (1) to the oxetanes (9) and (10) involves epimerization prior to the formation of the oxetane ring. The findings also indicate that this procedure may offer a flexible approach to the synthesis of highly substituted and functionalized chiral oxetanes, which could be relevant for the synthesis of oxetanocin and C-nucleoside analogues.
10.1021/ol1027267
The study focuses on the stereoelectronic effects that determine whether glycosylations proceed through oxacarbenium or α-sulfonium ion intermediates. The researchers investigated the influence of protecting groups and the constitution of the C-2 chiral auxiliary on the glycosylation pathway and the resulting anomeric outcome. They found that electron-withdrawing protecting groups, such as acetyl esters, favor the formation of α-sulfonium ions, leading to R-glycosides through an SN2-like displacement. In contrast, electron-donating protecting groups, like benzyl ethers, result in a mixture of anomers due to an equilibrium between sulfonium and oxacarbenium ions. The study also highlighted the importance of the chiral auxiliary's constitution, showing that certain substituents can enhance the stability of the sulfonium ion and promote selective glycosylation. These findings provide guidance for selecting glycosyl donors that can achieve exclusive 1,2-cis stereoselectivity in the synthesis of complex oligosaccharides.
10.1016/S0040-4020(01)86538-8
The research focuses on the asymmetric formation of C-N bonds in chiral enol ethers using (ethoxycarbonyl)methylene (EtO2CN2) or ethyl azidoformate (EtO2CN3) as reagents. The purpose of the study was to achieve a stereospecific introduction of an amino function by methylene addition to enol ethers containing a suitable chiral auxiliary. The researchers reported that the reaction of EtO2CN3 with chiral enol ethers at 120°C resulted in the formation of acetals of 2-(ethoxycarbonylammo)cyclohexanone with minor traces of amino ketone, except in one case where the amino ketone was the only detectable product. By employing ethyl N-{[(4-nitrophenyl)sulphonyl]oxy}carbamate at room temperature, they were able to directly obtain the desired amino ketone with high stereoselectivity. The study concluded that the room temperature amination reaction is a highly stereoselective process on chiral enol ethers using reactive reagents. Key chemicals used in the process include cyclohexanone, chiral 1,2-diols, triflic anhydride (TfOTMS), ethyl N-{[(4-nitrophenyl)sulphonyl]oxy}carbamate, and triethylamine, along with various enol ethers and acetals prepared from these starting materials.
C
