1,721,024 research outputs found
Huisgen cycloaddition in peptidomimetic chemistry
No full textDaniel Sejer Pedersen, and Andrew David Abel
Diphenylphosphinoyl-mediated synthesis of ketones
Get PDF© The Royal Society of Chemistry 2006.α-Diphenylphosphinoyl ketones are selectively and sequentially alkylated at the α-position. Double lithiation and selective alkylation occurs at the less stabilised γ-position. Dephosphinoylation of the alkylation products gives ketones. Mono-alkylation is selective, highly crystalline intermediates are formed and a one-pot strategy is possible. The method is ideally suited for the preparation of acid-sensitive ketones.David J. Fox, Daniel Sejer Pedersen, Stuart Warre
(2S,4'R,5'R)-(E)-tert-Butyl 2-acetyl-2-(2-oxo-5-phenyl-1,3- dioxolan-4-ylmethyl)-5-phenylpent-4-enoate
Get PDFThe title compound, C₂₇H₃₀O₆, was prepared by monodihydroxylation of the bis-olefin (E,E)-tert-butyl 2-acetyl-2-cinnamyl-5-phenylpent-4-enoate using standard Sharpless asymmetric dihydroxylation conditions, followed by treatment with 1,1'-carbonyl diimidazole. In the crystal structure, the phenyl rings form an intramolecular edge-to-face C-H… π contact with an interplanar angle of 56.4° and a H…centroid distance of 3.03 Å.David J. Fox ; Daniel Sejer Pedersen and Stuart Warre
LNA guanine and 2,6-diaminopurine. Synthesis, characterization and hybridization properties of LNA 2,6-diaminopurine containing oligonucleotides
No full textChristoph Rosenbohm, Daniel Sejer Pedersen, Miriam Frieden, Flemming R. Jensen, Susan Arent, Sine Larsen and Troels Kochhttp://www.elsevier.com/wps/find/journaldescription.cws_home/129/description#descriptio
Oligonucleotides containing a new type of acyclic, achiral nucleoside analogue: 1-[3-hydroxy-2-(hydroxymethyl)prop-1-enyl]thymine
No full textThomas Boesen, Daniel Sejer Pedersen, Brian M. Nielsen, Asger B. Petersen, Ulla Henriksen, Britta M. Dahl and Otto Dahlhttp://www.sciencedirect.com/science/journal/0960894
A simple, general and efficient ketone synthesis via alkylation and dephosphinoylation of beta-keto-diphenylphosphine oxides
No full text© Royal Society of Chemistry 2008Products of difficult ketone alkylation reactions can be made selectively via activation with a diphenylphosphinoyl group; subsequent dephosphinoylation is easily achieved in base.David J. Fox, Daniel Sejer Pedersen and Stuart Warre
Diphenylphosphinoyl chloride as a chlorinating agent - The selective double activation of 1,2-diols
Get PDF© The Royal Society of Chemistry 2006Treatment of 1,2-diols with diphenylphosphinoyl chloride in pyridine produces beta-chloroethyl phosphinates which react with complete control of stereochemistry to give epoxides and azido-alcohols, useful intermediates in cyclopropane synthesis.David J. Fox, Daniel Sejer Pedersen, Asger B. Petersen and Stuart Warre
Asymmetric cyclopropane synthesis via phosphine oxide mediated cascade reactions
Get PDFA silyloxy-THF has been converted into a cyclopropane containing three stereocentres as mixture of diastereoisomers. The mechanism of the reaction has been established and the source of stereochemical leakage proposed. An alternative stereospecific cascade reaction has been discovered.Thomas Boesen, David J. Fox, Warren Galloway, Daniel Sejer Pedersen, Charles R. Tyzack and
Stuart Warre
Asymmetric synthesis of cyclopropanes and dihydrofurans based on phosphine oxide chemistry
Get PDF© The Royal Society of Chemistry 2006The asymmetric synthesis of γ-azido trans-cyclopropyl ketones is accomplished via a short, simple and efficient sequence. The cyclopropanation step is achieved by an intramolecular nucleophilic ring closure, with a diphenylphosphinate leaving group, to give trans-cyclopropane exclusively. β-Keto-diphenylphosphine oxides cyclise to form optically active dihydrofurans. All possible diastereoisomers of dihydrofurans can be prepared selectively starting from the same olefin.David J. Fox, Sean Parris, Daniel Sejer Pedersen, Charles R. Tyzack and Stuart Warre
Asymmetric synthesis of orthogonally protected trans-cyclopropane c-amino acids via intramolecular ring closure
Get PDFThe synthesis of enantiomerically-enriched trans-cyclopropane amino- and hydroxy-acids can be achieved by intramolecular ring closure in moderate to good yields. The optically active cyclopropane precursors are easily prepared in a short sequence from inexpensive, commercially available olefins and tert-butyl acetate. Several leaving groups and bases were compared for the cyclopropanation step, showing that the diphenylphosphinate and tosyl leaving groups give the best results when used in combination with either LDA or NaHMDS.David J. Fox, Daniel Sejer Pedersen and Stuart Warre
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