The Experts below are selected from a list of 123 Experts worldwide ranked by ideXlab platform
Andrew G. Myers - One of the best experts on this subject based on the ideXlab platform.
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a solid supported enantioselective synthesis suitable for the rapid preparation of large numbers of diverse structural analogues of saframycin a
Journal of the American Chemical Society, 2002Co-Authors: Andrew G. Myers, Brian A. LanmanAbstract:A 10-step solid-supported, enantioselective synthesis suitable for the rapid preparation of large numbers of diverse structural analogues of saframycin A is described. The synthetic route, which bears analogy to solid-phase peptide synthesis, involves the directed condensation of N-protected α-Amino Aldehyde reactants. A novel dual linker was developed for attachment of intermediates to the solid support via a C-protective group, a substituted morpholino nitrile derivative. The route employs a novel diastereospecific cyclorelease mechanism, supports structural variation at multiple sites in the saframycin core, and obviates the need for chromatographic purification of the products or any intermediate. To demonstrate the feasibility of structural variation at multiple sites, a matrix of 16 saframycin A analogues was prepared by parallel synthesis with simultaneous variation of two sites. This work is notable not only as a preliminary step toward large-scale library construction but also as an example of th...
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One-step construction of the pentacyclic skeleton of saframycin A from a "Trimer" of alpha-Amino Aldehydes.
Organic letters, 2000Co-Authors: Andrew G. Myers, Daniel W. KungAbstract:The entire skeleton of the saframycin antitumor antibiotics is assembled in one remarkable transformation (8 --> 9) from an N-linked oligomer of three alpha-Amino Aldehyde components, a reaction pathway that may parallel the biosynthetic route to the saframycins.
Daniel W. Kung - One of the best experts on this subject based on the ideXlab platform.
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One-step construction of the pentacyclic skeleton of saframycin A from a "Trimer" of alpha-Amino Aldehydes.
Organic letters, 2000Co-Authors: Andrew G. Myers, Daniel W. KungAbstract:The entire skeleton of the saframycin antitumor antibiotics is assembled in one remarkable transformation (8 --> 9) from an N-linked oligomer of three alpha-Amino Aldehyde components, a reaction pathway that may parallel the biosynthetic route to the saframycins.
Gilles Dujardin - One of the best experts on this subject based on the ideXlab platform.
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3 2 route to quaternary oxaprolinol derivatives as masked precursors of disubstituted β3 β3 Amino Aldehyde
ChemInform, 2015Co-Authors: Pavlo Shpakkraievskyi, Amelle Mankou Makaya, Anne Beauchard, Arnaud Martel, Mathieu Y Laurent, Gilles DujardinAbstract:A new approach to enantiopure disubstituted oxaprolinol derivatives through diastereoselective [3+2]-cycloaddition of chiral cyclic ketonitrones to electron-rich and electron-poor dipolarophiles is presented.
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3 2 route to quaternary oxaprolinol derivatives as masked precursors of disubstituted β3 β3 Amino Aldehyde
European Journal of Organic Chemistry, 2015Co-Authors: Pavlo Shpakkraievskyi, Amelle Mankou Makaya, Anne Beauchard, Arnaud Martel, Mathieu Y Laurent, Gilles DujardinAbstract:Bicyclic isoxazolidines displaying one or two quaternary stereocenter(s) were formed starting from functional cyclic ketonitrones equipped with a phenyl glycinol chiral auxiliary. The products were engaged in stereocontrolled 1,3-dipolar cycloaddition reactions with a range of electron-rich and electron-poor dipolarophiles. A new reductive removal of the phenyl glycinol chiral auxiliary was introduced and was shown to afford chemoselectively a quaternary isoxazolidine derivative (of oxaprolinol-type) without cleaving the N–O isoxazolidine bond. Keeping the Aldehyde function masked as a cyclic pseudo-acetal, the liberated oxy-amine function was shown to be available for a pseudo-peptide coupling with various N-protected Amino acids. The isoxazolidine ring was opened by a reductive N–O bond cleavage, giving a pseudo-dipeptide that was C-terminated with an Aldehyde function.
Przemyslaw Kaliski - One of the best experts on this subject based on the ideXlab platform.
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c2 symmetric hemiaminal ethers and diamines new ligands for copper catalyzed desymmetrization of meso 1 2 diols and asymmetric henry reactions
Tetrahedron-asymmetry, 2013Co-Authors: Zbigniew Kaluza, Krzysztof Bielawski, Rafal Cwiek, Piotr Niedziejko, Przemyslaw KaliskiAbstract:Abstract The synthesis of novel, enantiomerically pure C 2 -symmetrical hemiaminal ethers and diamines containing piperazine core is presented. The key steps of the synthesis involve the dimerization of an in situ generated α-Amino Aldehyde into the corresponding cyclic bis-hemiaminal, followed by dehydration in the presence of a base to give a 7-oxa-2,5-diaza-bicyclo[2.2.1]heptane derivative, which can be regarded as a bicyclic bis-hemiaminal inner ether. These compounds represent a new class of molecule, with a structure unambiguously established for the first time. Finally, sodium triacetoxy-borohydride reduction gave the corresponding diamines. Both classes of compounds, new diamines and hemiaminal ethers, were shown to be good ligands for the copper(II)-catalyzed desymmetrization of meso -diols (up to 87% ee) and Henry reactions (up to 84% ee).
Peter Somfai - One of the best experts on this subject based on the ideXlab platform.
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total synthesis of alexine by utilizing a highly stereoselective 3 2 annulation reaction of an n tosyl alpha Amino Aldehyde and a 1 3 bis silyl propene
Chemistry: A European Journal, 2008Co-Authors: Martina Dressel, Per Restorp, Peter SomfaiAbstract:A novel route towards the polyhydroxylated pyrrolizidine alkaloid (+)-alexine has been developed. A key step in this synthesis is a highly stereoselective [3+2] annulation reaction of N-Ts-alpha-Amino Aldehyde 7 a (Ts=tosyl) and 1,3-bis(silyl)propene 8 a for the construction of the polyhydroxylated pyrrolidine subunit of the target molecule. Previous synthetic strategies rely on carbohydrates that require several protecting-group manipulations, thereby making the total number of steps relatively high. The [3+2] annulation strategy compares favorably with carbohydrate-based syntheses and constitutes a highly efficient entry to polyhydroxylated alkaloids.