- IBX-mediated oxidation of unactivated cyclic amines: application in highly diastereoselective oxidative Ugi-type and aza-Friedel-Crafts reactions
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The first o-iodoxybenzoic acid (IBX) mediated oxidation of unactivated amines to imines is described. A range of meso-pyrrolidines were shown to be suitable substrates. The chemical space was further explored with one-pot oxidative Ugi-type and aza-Friedel-Crafts reactions, which proved to be highly diastereoselective.
- De Graaff,Bensch,Van Lint, Matthijs J.,Ruijter,Orru
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p. 10108 - 10112
(2015/10/20)
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- Enantioselective synthesis of tricyclic amino acid derivatives based on a rigid 4-azatricyclo[5.2.1.02,6]decane skeleton
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An enantioselective route to four tricyclic amino acids and N-tosylamides, composed of a central norbornane framework with a 2-endo,3-endo-annelated pyrrolidine ring and a 5-endo-C1 or -C2 side chain, has been developed. A key intermediate was the chiral, N-Boc-protected ketone (1R,2S,6S,7R)-4-azatricyclo[5.2.1.02,6]decan-8-one, available from inexpensive endo-carbic anhydride in five steps and 47% yield. The rigid scaffold makes these amino acid derivatives promising candidates for β-turn-inducing building blocks in peptidomimetics and for chiral auxiliaries in asymmetric organocatalysis.
- Breuning, Matthias,Haeuser, Tobias,Mehler, Christian,Daeschlein, Christian,Strohmann, Carsten,Oechsner, Andreas,Braunschweig, Holger
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supporting information; experimental part
(2010/04/22)
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- Ring-opening Cross-metathesis (ROCM) as a novel tool for the ligation of peptides
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The development of ring-opening cross-metathesis (ROCM) as a novel tool for the site-specific ligation of peptide units is reported. The resulting structural units at the site of ligation resulting from ROCM resemble proline as well as other known ss-turn
- Michaelis, Simon,Blechert, Siegfried
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p. 2358 - 2368
(2008/02/04)
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- Molecular recognition of DNA by rigid [n]-polynorbornane-derived bifunctional intercalators: Synthesis and evaluation of their binding properties
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We have exploited the concept of multivalency in the context of DNA recognition, using novel chemistry to synthesize a new type of bis-intercalator with unusual sequence-selectivity. Bis-intercalation has been observed previously, but design principles for de novo construction of such molecules are not known. Our compounds feature two aromatic moieties projecting from a rigid, polynorbornane-based scaffold. The length and character of the backbone as well as the identity of the intercalators were varied, resulting in mono- or divalent recognition of the double helix with varying affinity. Our lead compound proved to be a moderately sequence-selective bis-intercalator with an unwinding angle of 27° and a binding constant of about 8 μM. 9-Aminoacridine rings were preferred over acridine carboxamides or naphthalimides, and a rigid [3]-polynorbornane scaffold was superior to a [5]-polynorbornane. The flexibility of the linker connecting the rings to the scaffold, although less influential, could affect the strength and character of the DNA binding.
- Van Vliet, Liisa D.,Ellis, Tom,Foley, Patrick J.,Liu, Ligong,Pfeffer, Frederick M.,Russell, Richard A.,Warrener, Ronald N.,Hollfelder, Florian,Waring, Michael J.
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p. 2326 - 2340
(2008/02/05)
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- Synthesis, structure, and transformations of new endic anhydride derivatives
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4-Azatricyclo[5.2.1.02,6]dec-8-ene and its N-phenyl derivative were synthesized by reaction of endic anhydride with amines, transformation of the amido acids thus obtained to imides, and subsequent reduction of the latter with lithium aluminum hydride. The unsubstituted tricyclic amine was brought into reactions with electrophilic reagents: p-toluenesulfonyl chloride, p-toluoyl chloride, m-tolyl isocyanate, phenyl isothiocyanate, and endic anhydride to obtain a number of new derivatives; also, the corresponding salt with 1-adamantanecarboxylic acid was isolated. N-(p-Tolylsulfonyl)- and N-(m-tolylcarbamoyl)-4-azatricyclo[5.2.1.02,6]dec-8-enes were oxidized to the corresponding 8,9-epoxy derivatives with monoperoxyphthalic acid. The structure of the products was confirmed by the data of IR, 1H and 13C NMR, and mass spectra. The molecular structures of N-(p-iodophenyl)bicyclo[2.2.1]hept-2-ene-endo-5,endo-6-dicarboximide and N-phenyl-4-azatricyclo[5.2.1.02,6]dec-8-ene were established by X-ray analysis.
- Tarabara,Kas'yan,Krishchik,Shishkina,Shishkin,Kas'yan
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p. 1299 - 1308
(2007/10/03)
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- Nitrosamine Photolysis as a Synthetic Method: The Addition of Aminium Radicals to Unsaturated Carbon-Carbon Bonds
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Acid complexed nitrosamines decompose from their lowest singlet excited state to gine aminium radicals and nitric oxide radical transients.Aminium radicals initiate addition of various unsaturated groups to give 1-amino-2-nitroso compounds under an inert atmosphere, or 1-amino-2-nitrates under oxygen.In this report, photoaddition of nitroamines to olefins, acetylenes and fused aromatic hydrocarbons, and the subsequent transformations of the intermediates are described.Aminium radical initiated intramolecular cyclization to prepare tetracyclic aza compounds is also described.While photoaddition of nitrosamines to 4-propenylanisole or 3-butenol wes efficient, that to 3-butenyl benzoates under oxidative conditions was only fair, obviously due to the presence of a benzene ring.The oxidative photoaddition to 3-butenyl halide was followed by spontaneous cyclization to an azaspiro compound.The photoaddition to phenyl-substituted acetylenes gave β-nitroso enamines which hydrolyzed to diketomonoximes under neitral conditions but decomposed extensively under acidic conditions.Certain fused aromatic hydrocarbons acted as singlet sensitizers as well as substrates to induce similar addition giving amino nitroso adducts.These adducts took different courses of conversion dependent on reaction conditions, and on steric and electronic factors.
- Chow, Yuan L.,Colon, Carlos J.,Chang, Dawid W. L.,Pillay, K. Somasekharen,Lochart Robert D.,Tezuka, Takahiro
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p. 622 - 634
(2007/10/02)
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- SYNTHESIS OF COMPOUNDS OF THE BICYCLOHEPTANE SERIES THAT ARE FUSED WITH AN OXAZECINE RING
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Derivatives of the bicycloheptane series that are condensed with an oxazecine ring were obtained.A number of transformations of the compounds obtained were realized.Data from the IR, NMR, and mass spectra that confirm the structures of the synthesized compounds are presented.
- Levchenko, N. K.,Segal', G. M.,Torgov, I. V.
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p. 251 - 256
(2007/10/02)
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