931-59-9Relevant articles and documents
Bifunctionalized Allenes. Part XII. Electrophilic Cyclization and Addition Reactions of 4-Sulfinylated or 4-Sulfonylated Allenecarboxylates
Ivanov, Ivaylo K.,Parushev, Ivaylo D.,Christov, Valerij Ch
, p. 1503 - 1513 (2014)
Reaction of 4-sulfinylated or 4-sulfonylated allenecarboxylates with different electrophilic reagents such as sulfuryl chloride, bromine, benzenesulfenyl, and benzeneselenenyl chlorides takes place with 5-endo-trig cyclization or 3,2-addition reaction depending on the kind of the substituent at the sulfur atom. Treatment of 4-(benzenesulfinyl)-allenoates with electrophiles gives 5-(benzenesulfinyl)-2,5-dihydrofuran-2-ones as a result of the neighboring carboxylate group participation in the cyclization. On the other hand, (3E)-4-(methansulfonyl)alk-3-enoates were prepared by chemo-, regio-, and stereoselective electrophilic addition to the C2-C3-double bond in the allenoate moiety of 4-(methanesulfonyl)allenecarboxylates. When R1 = Me, the treatment with electrophiles gives mixtures of (3E)-4-(methanesulfonyl)alk-3-enoates and (3E)-4-(methanesulfonyl)-2-methylenealk-3-enoates with ratios of about 1.6:1 as a result of addition and elimination reactions. A possible mechanism involving cyclization, addition, and elimination reactions of the 4-sulfinylated or 4-sulfonylated allenecarboxylates is proposed.
Group 4 metal complexes bearing thioetherphenolate ligands. Coordination chemistry and ring-opening polymerization catalysis
Della Monica, Francesco,Luciano, Ermanno,Roviello, Giuseppina,Grassi, Alfonso,Milione, Stefano,Capacchione, Carmine
, p. 2830 - 2841 (2014)
A series of group 4 metal complexes 1-4 (1 = (t-BuOS) 2Ti(O-i-Pr)2; 2 = (t-BuOS)2Zr(O-t- Bu)2; 3 = (t-BuOS)2Hf(O-t-Bu)2; 4 = (CumOS)2Zr(O-t-Bu)2) supported by two phenolate bidentate ligands (t-BuOS-H = 4,6-di-tert-butyl-2- phenylsulfanylphenol and CumOS-H = 4,6-dicumyl-2- phenylsulfanylphenol) were synthesized by the reaction of appropriate metal tetra(alkoxide)s with 2 equiv of the ligands. The X-ray structure of 2 revealed that the two ligands were κ2-chelated to the metal center with two phenoxy groups in trans positions and the two thioether moieties in cis positions. VT NMR analysis revealed a fast inversion of configuration at the metal center. Complexes 1-4 promoted the ring-opening polymerization (ROP) of lactide and ε-caprolactone. Complex 4 exhibited the highest activity with a pseudo-first-order rate constant of 0.061 ± 0.003 min-1 at 100 °C, which compares favorably with those reported for the most active group 4 complexes. Polymerizations were well-controlled, giving predictable molecular weights and narrow molecular weight distributions. Essentially atactic PLA were obtained in the ROP of rac-lactide. A DFT study on ROP promoted by these complexes highlighted the importance of the coordinative flexibility of the ancillary ligand to promote monomer coordination at the reactive metal center. In presence of isopropanol, lower PDI indexes and molecular weights of the PLAs proportional to the equivalents of isopropanol suggested that adequate conditions for effective "immortal" polymerizations were achieved. More interestingly, these catalysts promoted the copolymerization of l-lactide and ε-caprolactone. The microstructure disclosed by 13C NMR analysis and the thermal behavior exhibited in DSC studies indicated a random distribution of the two monomer along the polymer chain.
Bifunctionalized allenes. Part XV. Synthesis of 2,5-dihydro-1,2- oxaphospholes by electrophilic cyclization reaction of phosphorylated α-hydroxyallenes
Ismailov, Ismail E.,Ivanov, Ivaylo K.,Christov, Valerij Ch.
, p. 11056 - 11076 (2014)
This paper discusses a reaction of phosphorylated α-hydroxyallenes with protected or unprotected hydroxy groups involving 5-endo-trig cyclizations. Various electrophilic reagents such as sulfuryl chloride, bromine, benzenesulfenyl and benzeneselenenyl chlorides have been applied. The paper describes the reaction of 1-hydroxyalkyl-1,2-dienephosphonates with electrophiles that produces 2-methoxy-2-oxo-2,5-dihydro-1,2-oxaphospholes due to the participation of the phosphonate neighbouring group in the cyclization. On the other hand, (1E)-alk-1-en-1-yl phosphine oxides were prepared as mixtures with 2,5-dihydro-1,2-oxaphosphol-2-ium halides in a ratio of about 1:2 by chemo-, regio, and stereoselective electrophilic addition to the C 2-C3-double bond in the allene moiety and subsequent concurrent attack of the external (halide anion) and internal (phosphine oxide group) nucleophiles. The paper proposes a possible mechanism that involves cyclization and additional reactions of the phosphorylated α- hydroxyallenes.
Tryptophan trimers and tetramers inhibit dengue and Zika virus replication by interfering with viral attachment processes
Fikatas, Antonios,Meyen, Eef,Noppen, Sam,Pannecouque, Christophe,Schols, Dominique,Vervaeke, Peter,Camarasa, María-José,Martí-Marí, Olaia,Martínez-Guald, Belén,San-Félix, Ana
, (2020)
Here, we report a class of tryptophan trimers and tetramers that inhibit (at low micromolar range) dengue and Zika virus infection in vitro. These compounds (AL family) have three or four peripheral tryptophan moieties directly linked to a central scaffold through their amino groups; thus, their carboxylic acid groups are free and exposed to the periphery. Structure-activity relationship (SAR) studies demonstrated that the presence of extra phenyl rings with substituents other than COOH at the N1 or C2 position of the indole side chain is a requisite for the antiviral activity against both viruses. The molecules showed potent antiviral activity, with low cytotoxicity, when evaluated on different cell lines. Moreover, they were active against laboratory and clinical strains of all four serotypes of dengue virus as well as a selected group of Zika virus strains. Additional mechanistic studies performed with the two most potent compounds (AL439 and AL440) demonstrated an interaction with the viral envelope glycoprotein (domain III) of dengue 2 virus, preventing virus attachment to the host cell membrane. Since no antiviral agent is approved at the moment against these two flaviviruses, further pharmacokinetic studies with these molecules are needed for their development as future therapeutic/prophylactic drugs.
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Bontempelli et al.
, p. 73,75 (1978)
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A general and concise enantioselective divergent approach to 13-alkyl-substituted ionones
Bugoni, Serena,Merlini, Valentina,Porta, Alessio,Zanoni, Giuseppe,Vidari, Giovanni
, p. 1540 - 1553 (2014)
A novel enantioselective divergent route to 13-alkyl derivatives of a- and g-ionone, important components of perfumes and fragrances, is reported. This relatively short and convenient methodology takes advantage of the use of a common intermediate, easily obtained from highly enantiomerically enriched (S)-a-ionone, which avoids the separate installation of the butenone side chain at C(6) for each analog. Olfactory evaluation of synthesized compounds reconfirmed the influence of the hydrophobic interactions of alkyl substituents at C(5) with olfactory receptors (ORs) in the chemoreception of ionones, and suggested that a synperiplanar orientation of C(13) and the lateral chain is the better geometry fitting OR's cavity.
Bifunctional Polyene Cyclizations: Synthetic Studies on Pimarane Natural Products
Feilner, Julian M.,Magauer, Thomas,Plangger, Immanuel,Wurst, Klaus
supporting information, p. 12410 - 12421 (2021/07/28)
Polyene cyclizations generate molecular complexity from a linear polyene in a single step. While methods to initiate these cyclizations have been continuously expanded and improved over the years, the majority of polyene substrates are still limited to simple alkyl-substituted alkenes. In this study, we took advantage of the unique reactivity of higher-functionalized bifunctional alkenes. The realization of a polyene tetracyclization of a dual nucleophilic aryl enol ether involving a transannular endo-termination step enabled the total synthesis of the tricyclic diterpenoid pimara-15-en-3α-8α-diol. The highly flexible and modular route allowed for the preparation of a diverse library of cyclization precursors specifically designed for the total synthesis of the tetracyclic nor-diterpenoid norflickinflimiod C. The tetracyclization of three diversely substituted allenes enabled access to complex pentacyclic products and provided a detailed insight into the underlying reaction pathways.
Unified Approach to Benzo[ d]thiazol-2-yl-Sulfonamides
Zále?ák, Franti?ek,Ková?, Ond?ej,Lachetová, Eli?ka,?t'astná, Nikola,Pospí?il, Ji?í
supporting information, p. 11291 - 11309 (2021/09/07)
In this paper, we report a unified approach to N-substituted and N,N-disubstituted benzothiazole (BT) sulfonamides. Our approach to BT-sulfonamides starts from simple commercially available building blocks (benzo[d]thiazole-2-thiol and primary and secondary amines) that are connected via (a) a S oxidation/S-N coupling approach, (b) a S-N coupling/S-oxidation sequence, or via (c) a S-oxidation/S-F bond formation/SuFEx approach. The labile N-H bond in N-monoalkylated BT-sulfonamides (pKa (BTSO2N(H)Bn) = 3.34 ± 0.05) further allowed us to develop a simple weak base-promoted N-alkylation method and a stereoselective microwave-promoted Fukuyama-Mitsunobu reaction. N-Alkyl-N-aryl BT-sulfonamides were accessed with the help of the Chan-Lam coupling reaction. Developed methods were further used in stereo and chemoselective transformations of podophyllotoxin and several amino alcohols.
