- Synthesis and spin trapping properties of polystyrene supported trifluoromethylated cyclic nitrones
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Polystyrene supported fluorinated cyclic nitrone spin-traps: Resin-2-HFDMPO (2-hydroxymethyl-2-methyl-5-(trifluoromethyl)-3,4-dihydro-2H-pyrrole-1-oxide) and Resin-2-PFDMPO (2-(3-hydroxypropyl)-2-methyl-5-(trifluoromethyl)-3,4-dihydro-2H-pyrrole 1-oxide) containing a trifluoromethyl pyrroline-N-oxide core were developed to detect free radicals under flow conditions. A continuous flow EPR technique was used to evaluate the spin trapping properties of these tethered nitrones. While both resins trapped radicals, polymer supported nitrone Resin-2-PFDMPO with a longer and more flexible linker showed a more information rich spectrum than Resin-2-HFDMPO.
- Earla, Aruna,Walter, Eric D.,Braslau, Rebecca
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- Asymmetric Organocatalytic Sequential Reaction of Structurally Complex Cyclic Hemiacetals and Functionalized Nitro-olefins to Synthesize Diverse Heterocycles
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Structurally complex cyclic hemiacetals bearing a racemic tetrasubstituted stereocenter have been prepared in a concise manner and were successfully used in an organocatalytic enantioselective sequence to react with functionalized nitro-olefins, providing bicyclic acetal-containing compounds as two separable epimers with excellent stereoselectivity. The reaction showed broad substrate scope, with respect to the starting hemiacetals. Moreover, this protocol allows the synthetic transformation of the products to various interesting heterocyclic compounds with substantial structural diversity and broad functionality.
- Pei, Jun-Ping,Chen, Ying-Han,Liu, Yan-Kai
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supporting information
p. 3609 - 3612
(2018/06/26)
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- Catalytic enantioselective protonation of nitronates utilizing an organocatalyst chiral only at sulfur
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The highly enantioselective protonation of nitronates formed upon the addition of α-substituted Meldrums acids to terminally unsubstituted nitroalkenes is described. This work represents the first enantioselective catalytic addition of any type of nucleophile to this class of nitroalkenes. Moreover, for the successful implementation of this method, a new type of N-sulfinyl urea catalyst with chirality residing only at the sulfinyl group was developed, thereby enabling the incorporation of a diverse range of achiral diamine motifs. Finally, the Meldrums acid addition products were readily converted to pharmaceutically relevant 3,5-disubstituted pyrrolidinones in high yield.
- Kimmel, Kyle L.,Weaver, Jimmie D.,Lee, Melissa,Ellman, Jonathan A.
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supporting information; scheme or table
p. 9058 - 9061
(2012/07/14)
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- Polyamine alcohol derivatives
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A compound having formula (I) wherein R1 is methyl or ethyl; R2 is hydrogen, methyl, CH2C(NH2)(R1)(CH2OH) or R2 groups combine to form a difunctional C2-C6 alkyl group; and X is a difunctional group selected from the group consisting of C2-C20 alkyl, C5-C20 cycloalkyl, C6-C10 aryl, C8-C20 aryl alkyl, C4-C20 heteroalkyl or C10-C20 aryl heteroalkyl.
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Page/Page column 3-4
(2012/07/03)
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- A recyclable organocascade reaction system: Stereoselective precipitation of optically active cis-δ-lactols with quaternary stereocenters during the Michael-hemiacetalization reaction
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A cascade Michael-hemiacetalization reaction between β-substituted β-nitroethanols and α,β-unsaturated aldehydes is described, which provides a convenient and efficient synthesis for cis-δ-lactols with quaternary stereocenters in moderate yields with excellent enantioselectivity. Based on the selective precipitation of cis-δ-lactols, which were isolated by filtration, the catalytic system in the filtrate can be reused directly and recycled for eight times without any obvious deterioration in enantioselectivity. Copyright
- Zhang, Fanglin,Wei, Mohui,Dong, Junfang,Zhou, Yirong,Lu, Dengfu,Gong, Yuefa,Yang, Xiangliang
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supporting information; experimental part
p. 2875 - 2880
(2011/01/05)
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- Process for the preparation of morpholinones as light stabilizers
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The instant invention discloses a process for preparation of compounds of the formula (I), wherein the general symbols are as defined in claim 1, which process comprises reacting a compound of formula (II), wherein the general symbols are as defined in claim 1, with a compound of the formula (III), wherein R5 is as defined in slaim 1. The compounds of the formula (II) are new and useful as stabilizers for protecting organic materials, in particular synthetic polymers, reprographic materials or coating materials against oxidative, thermal or light-induced degradation.
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- Free radical addition reactions of allylic sulfones to alkenes
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Intermolecular radical reactions involving formal addition of the sulfonyl and allyl fragments of an allylic sulfone across the double bond of an alkene are described. Reactions are most successful when the allylic sulfone has an electron withdrawing group at the 2-position. Only monosubstituted alkenes give useful yields of adducts, though both electron withdrawing and electron donating substituents are effective.
- Harvey, Iain W.,Phillips, Eifion D.,Whitham, Gordon H.
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p. 6493 - 6508
(2007/10/03)
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- Regioselective synthesis of 5-unsubstituted benzyl pyrrole-2-carboxylates from benzyl isocyanoacetate
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A general synthesis of 5-unsubstituted benzyl pyrrole-2-carboxylates was developed based on the reaction of β-nitroacetates with benzyl isocyanoacetate. The advantage of this route over other pyrrole syntheses was the regiochemical control of the substitution pattern on the pyrrole ring.
- Ono,Katayama,Nisyiyama,Ogawa
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p. 707 - 710
(2007/10/02)
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- Reactions of O,O-Diprotonated Nitro Olefins with Benzenes. Formations of Phenylacetones, 4H-1,2-Benzoxazines and Biarylacetone Oximes
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O,O-Diprotonated nitro olefins undergo three alternative electrophilic reactions which yield α-phenylacetones, 4H-1,2-benzoxazines and biphenylacetone oximes depending on the reaction conditions (temperature and time) and aromatic substrates.Although these reactions are seemingly divergent, a common intermediate of a phenylated protonated aci-nitro species, derived from the dication, is postulated to be involved in the reactions.Furthermore, the formation of benzoxazines and biphenylacetone oximes can be interpreted in terms of participation of novel chemical species with phenylethylene dication character derived from the common intermediate.
- Ohwada, Tomohiko,Okabe, Kazuaki,Ohta, Toshiharu,Shudo, Koichi
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p. 7539 - 7555
(2007/10/02)
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- A New Method for Obtaining Isotopic Fractionation Data at Multiple Sites in Rapidly Exchanging Systems
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A new method for rapidly and conveniently obtaining isotopic fractionation factors in dilute aqueous solutions of compounds containing rapidly exchanging OH, NH, and SH groups is described.Shifts in the positions of NMR peaks for spectroscopically observable nuclei induced by isotopic substitution are the basis of this procedure which has the unique capability of separately measuring the isotopic exchange constants simultaneously for several different groups in the same molecule.The results for a series of alcohols, amines, thiols, phenols, acids, and amides with use of 13C NMR spectroscopy are reported.Atypically low values of Kfrac are observed in several cases, indicating that there are strong internal hydrogen bonds in competition with those to water, yielding conformational information.
- Jarret, Ronald M.,Saunders, Martin
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p. 2648 - 2654
(2007/10/02)
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