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1.
Dr. Pushpak Mizar Alessandra Burrelli Erika Günther Martin Söftje Prof. Dr. Umar Farooq Prof. Dr. Thomas Wirth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13113-13116
A new chiral thiohydantoin catalyst is used for the stereoselective iodoamination of alkenes. N‐iodosuccinimide as the source of the electrophilic iodine is activated by catalytic amounts of different additives which also influence the regioselectivity of some cyclizations. 相似文献
2.
Tushar S. Basu Baul Archana Mizar Eleonora Rivarola Michal Hol?apek Ulli Englert 《Journal of organometallic chemistry》2006,691(16):3416-3425
A series of cis-bis{5-[(E)-2-(aryl)-1-diazenyl]quinolinolato}diphenyltin(IV) complexes have been synthesized and characterized by 1H, 13C, 119Sn NMR, ESI-MS, IR and 119mSn Mössbauer spectroscopic techniques in combination with elemental analysis. The structures of a ligand L6H (i.e., 5-[(E)-2-(4-ethoxyphenyl)-1-diazenyl]quinolin-8-ol) and three diphenyltin(IV) complexes, viz., Ph2Sn(L1)2 · (CH3)2CO (1), Ph2Sn(L4)2 (4) and Ph2Sn(L5)2 (5) (L = 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-ol: aryl = phenyl - (L1H); 4′-methylphenyl - (L4H) and 4′-bromophenyl - (L5H)) were determined by single crystal X-ray diffraction. In general, the complexes were found to adopt a distorted cis-octahedral arrangement around the tin atom. These complexes retain their solid-state structure in non-coordinating solvent as evidenced by 119Sn NMR spectroscopic results. The in vitro cytotoxicity of 1 is reported and compared with Ph2Sn(Ox)2 (Ox = deprotonated quinolin-8-ol) against seven well characterized human tumor cell lines. 相似文献
3.
Pushpak Mizar 《Tetrahedron letters》2006,47(44):7823-7826
Substituted 2H-1,4-benzoxazines were synthesized from substituted 2-amino phenols and 1,2-dibromoethane using K2CO3 in good to excellent yields. The cyclized products were further reacted with alkyl bromides to obtain the desired N-substituted 3,4-dihydro-2H-1,4-benzoxazines. 相似文献
4.
Flexible Stereoselective Functionalizations of Ketones through Umpolung with Hypervalent Iodine Reagents
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Dr. Pushpak Mizar Prof. Dr. Thomas Wirth 《Angewandte Chemie (International ed. in English)》2014,53(23):5993-5997
The functionalization of carbonyl compounds in the α‐position has gathered much attention as a synthetic route because of the wide biological importance of such products. Through polarity reversal, or “umpolung”, we show here that typical nucleophiles, such as oxygen, nitrogen, and even carbon nucleophiles, can be used for addition reactions after tethering them to enol ethers. Our findings allow novel retrosynthetic planning and rapid assembly of structures previously accessible only by multistep sequences. 相似文献
5.
Dr. Pushpak Mizar Aragorn Laverny Mohammad El‐Sherbini Dr. Umar Farid Dr. Michael Brown Florence Malmedy Prof. Dr. Thomas Wirth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9910-9913
Vicinal diamines constitute one the most important functional motif in organic chemistry because of its wide occurrence in a variety of biological and pharmaceutical molecules. We report an efficient metal‐free, highly stereoselective intramolecular diamination using a novel chiral hypervalent iodine reagent together with its application as an efficient catalyst for the synthesis of diamines. 相似文献
6.
Pushpak Mizar 《Tetrahedron letters》2008,49(36):5283-5285
A series of fused pyrimidine derivatives were synthesized by the three-component reaction of an aryl aldehyde, urea, or guanidine in ethyl alcohol/dioxane in presence of 1-methyl-1H-pyrrol-2(3H)-one 1, 1-methylpiperidin-2-one 2, 1-methylindolin-2-one 3, or 1,3-dimethyl-dihydropyrimidine-2,4-dione 9 at 80 °C catalyzed by KF-Al2O3. For example, when 1-methyl-1H-pyrrol-2(3H)-one 1, arylaldehyde 4, and urea 5 were treated with KF-Al2O3 in ethyl alcohol at 80 °C for 3-5 h, we obtained pyrrolo[2,3-d]pyrimidine derivatives in good yield. 相似文献
7.
Tushar S. Basu Baul Archana Mizar Giuseppe Ruisi Monique Biesemans 《Journal of organometallic chemistry》2009,694(14):2142-4247
Reactions of nBu2SnCl(L1) (1), where L1 = acid residue of 5-[(E)-2-(4-methoxyphenyl)-1-diazenyl]quinolin-8-ol, with various substituted benzoic acids in refluxing toluene, in the presence of triethylamine, yielded dimeric mixed ligand di-n-butyltin(IV) complexes of composition [nBu2Sn(L1)(L2-6)]2 where L2 = benzene carboxylate (2), L3 = 2-[(E)-2-(2-hydroxy-5-methylphenyl)-1-diazenyl]benzoate (3), L4 = 5-[(E)-2-(4-methylphenyl)-1-diazenyl]-2-hydroxybenzoate (4), L5 = 2-{(E)-4-hydroxy-3-[(E)-4-chlorophenyliminomethyl]-phenyldiazenyl}benzoate (5) and L6 = 2-[(E)-(3-formyl-4-hydroxyphenyl)-diazenyl]benzoate (6). All complexes (1-6) have been characterized by elemental analyses, IR, 1H, 13C and 117Sn NMR and 119Sn Mössbauer spectroscopy and their structures were determined by X-ray crystallography, complemented by 117Sn CP-MAS NMR spectroscopy studies in the solid state. The crystal structure of 1 reveals a distorted trigonal bipyramidal coordination geometry around the Sn-atom where the Cl- and N-atoms of ligand L1 occupy the axial positions. In complexes 2-5, the molecules are centrosymmetric dimers in which the Sn-atoms are connected by asymmetric μ-O bridges through the quinoline O-atom to give an Sn2O2 core. The differences in the Sn-O bond lengths within the bridge range from 0.28 to 0.48 Å, with the longer of the Sn-O distances being in the range 2.56-2.68 Å and the most symmetrical bridge being in 5. The carboxylate group is almost symmetrically bidentate coordinated to the tin atom in 5 (Sn-O distances of 2.327(2) and 2.441(2) Å), unlike the other complexes in which the distance of the carboxylate carbonyl O-atom from the tin atom is in the range 2.92-3.03 Å. The structure of 5 displays a more regular pentagonal bipyramidal coordination geometry about each tin atom than in 2-4. In contrast, the centrosymmetric dimeric structure of 6 involves asymmetric carboxylate bridges, resulting in a different Sn2C2O4 motif. The Sn-O bond lengths in the bridge differ by about 0.6 Å, with the longer distance involving the carboxylate carbonyl O-atom (2.683(2) and 2.798(2) Å for two molecules in the asymmetric unit). The carboxylate carbonyl O-atom has a second, even longer intramolecular contact to the Sn-atom to which the carboxylate group is primarily coordinated, with these Sn?O distances being as high as 3.085(2) and 2.898(2) Å. If the secondary interactions are considered, all the di-n-butyltin(IV) complexes (2-6) display a distorted pentagonal bipyramidal arrangement about each tin atom in which the n-butyl groups occupy the axial positions. 相似文献
8.
Pushpak Mizar 《Tetrahedron letters》2009,50(25):3088-3231
The procedures described herein provide a facile method for the synthesis of pyrazolo[3,4-b]pyridine and pyrazolo[1,5-a]pyrimidine by reacting N-substituted or unsubstituted-pyrazol-5(4H)-one, aryl-oxoketene dithioacetals and alkyl amide. The products were obtained in moderate to good yield. The effects of the solvents and substitution have also been described. 相似文献
9.
Tushar S. Basu Baul Archana Mizar Ulli Englert 《Journal of organometallic chemistry》2008,693(10):1751-1758
Reactions of sodium 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-olates (LH, where the aryl group is an R-substituted phenyl ring such that for L1H: R = H; L2H: R = 2′-CH3; L3H: R = 3′-CH3; L4H: R = 4′-CH3; L5H: R = 4′-OCH3 and L6H: R = 4′-OC2H5) with Ph3SnCl in a 1:1 molar ratio yielded complexes of composition Ph3SnL. The complexes have been characterized by 1H, 13C, 119Sn NMR, IR and 119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of Ph3SnL1 · 0.5C6H6 (1), Ph3SnL2 (2), Ph3SnL5 · C6H6 (5) and Ph3SnL6 · 0.5C6H6 (6) were determined. The results of the X-ray studies indicated that the benzene solvated compounds 1, 5 and 6 are distorted square pyramid, with one of the phenyl C atoms in the apex while the ligand arrangement around central Sn atom in 2 is distorted trigonal-bipyramidal, with a phenyl C and the oxinato N atoms in axial positions. 相似文献
10.
Seung Seo Lee Pushpak Mizar Ozge Kucuk 《Phosphorus, sulfur, and silicon and the related elements》2020,195(6):454-463
AbstractThe reactions of cyclotriphosphazene (1) with 2-(2-hydroxyethylamino)-ethanol (2) were investigated. 2-(2-hydroxyethylamino)-ethanol (2) is a tri-functional reagent consisting of both aliphatic hydroxyl and the secondary amino groups and its nucleophilic substitution reactions with cylotriphosphazene can lead to different product types; open chain, spiro, ansa, bridged and their mixtures. The reactions with one, two and three equimolar ratios of 2-(2-hydroxyethylamino)-ethanol, in the presence of NaH at 0–10?°C and at room temperature gave the following cyclotriphosphazene derivatives: one mono-spiro, N3P3Cl4[O–(CH2)2–NH–(CH2)2–O] (3, 1:1, r.t.); its isomer mono-ansa (5, 1:1, r.t.); one dispiro, N3P3Cl2[O–(CH2)2–NH–(CH2)2–O]2 (4, 1:1, r.t.); its isomer spiro-ansa (6, 1:2, r.t.); and one single-bridged compound with spiro substituted units, N3P3Cl3[O–(CH2)2–NH–(CH2)2–O]3N3P3Cl3 (7, 1:3, at 0–10?°C); as well as single-, N3P3Cl5[O–(CH2)2–NH–(CH2)2–O]N3P3Cl5 (8, 1:2, r.t.), double-, N3P3Cl4[O–(CH2)2–NH–(CH2)2–O]2N3P3Cl4 (9, 1:2, r.t.), and tri-bridged, N3P3Cl3[O–(CH2)2–NH–(CH2)2–O]3N3P3Cl3 (10, 1:3, at 0–10?°C) derivatives. Triple-bridged derivative is the major product in this system. The structures of the novel-derived compounds were characterized by TLC-MS, FT-IR, elemental analysis, 1H, and 31P NMR spectral. 相似文献