176-25-0Relevant academic research and scientific papers
Asymmetric spiroacetalization catalysed by confined Bronsted acids
Coric, Ilija,List, Benjamin
, p. 315 - 319 (2012)
Acetals are molecular substructures that contain two oxygen-carbon single bonds at the same carbon atom, and are used in cells to construct carbohydrates and numerous other molecules. A distinctive subgroup are spiroacetals, acetals joining two rings, which occur in a broad range of biologically active compounds, including small insect pheromones and more complex macrocycles. Despite numerous methods for the catalytic asymmetric formation of other commonly occurring stereocentres, there are few approaches that exclusively target the chiral acetal centre and none for spiroacetals. Here we report the design and synthesis of confined Bronsted acids based on a C 2-symmetric imidodiphosphoric acid motif, enabling a catalytic enantioselective spiroacetalization reaction. These rationally constructed Bronsted acids possess an extremely sterically demanding chiral microenvironment, with a single catalytically relevant and geometrically constrained bifunctional active site. Our catalyst design is expected to be of broad utility in catalytic asymmetric reactions involving small and structurally or functionally unbiased substrates. 2012 Macmillan Publishers Limited. All rights reserved.
An Intramolecular Iodine-Catalyzed C(sp3)?H Oxidation as a Versatile Tool for the Synthesis of Tetrahydrofurans
Br?se, Stefan,Koch, Vanessa
supporting information, p. 3478 - 3483 (2021/07/22)
The formation of ubiquitous occurring tetrahydrofuran patterns has been extensively investigated in the 1960s as it was one of the first examples of a non-directed remote C?H activation. These approaches suffer from the use of toxic transition metals in overstoichiometric amounts. An attractive metal-free solution for transforming carbon-hydrogen bonds into carbon-oxygen bonds lies in applying economically and ecologically favorable iodine reagents. The presented method involves an intertwined catalytic cycle of a radical chain reaction and an iodine(I/III) redox couple by selectively activating a remote C(sp3)?H bond under visible-light irradiation. The reaction proceeds under mild reaction conditions, is operationally simple and tolerates many functional groups giving fast and easy access to different substituted tetrahydrofurans.
Chiral imidodiphosphates and derivatives thereof
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Paragraph 0079; 0080; 0081; 0090; 0091, (2013/07/25)
The invention relates to chiral imidodiphosphates and derivatives thereof having the general formula I, The compounds are suitable as chiral Br?nsted acid catalysts, phase-transfer catalysts, chiral anions for organic salts, metal salts or metal complexes for catalysis.
CHIRAL IMIDODIPHOSPHATES AND DERIVATIVES THEREOF
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Page/Page column 25; 26; 27, (2013/07/25)
The invention relates to chiral imidodiphosphates and derivatives thereof having the general formula I, The compounds are suitable as chiral Br?nsted acid catalysts, phase-transfer catalysts, chiral anions for organic salts, metal salts or metal complexes for catalysis.
Tellurium/lithium exchange reactions in the synthesis of spiroketals and 1,6-dioxygenated systems
Dos Santos, Alcindo A.,Princival, Jefferson L.,Comasseto, Jo?o V.,de Barros, Simone M.G.,Neto, José E. Brainer
, p. 5167 - 5172 (2008/02/01)
1,4-C,O-dianions have been generated through concomitant acid/base and tellurium/lithium exchange reactions. The di-lithium salts were transmetallated with cerium chloride to the corresponding di-cerium salts and subsequently reacted with lactones and carboxylic acid anhydrides to yield the respective spiroketals. The di-lithium entities were also converted into the corresponding cyanocuprates that add in a 1,4-manner to 2-cyclohexen-1-one to form 1,6-dioxygenated compounds.
Synthesis of spiroacetal pheromones via metalated hydrazones
Enders,Dahmen,Dederichs,Gatzweiler,Weuster
, p. 1013 - 1019 (2007/10/02)
The synthesis of simple alkyl substituted spiroacetals by α,α'-alkylation of metalated acetone dimethylhydrazone with appropriate electrophiles and subsequent acid catalyzed cleavage and ring closure of the products is described.
SPIROACETALS FROM ACETONE AND OXIRANES - A SIMPLE ROUTE TO OPTICALLY ACTIVE 1,6-DIOXASPIRONONANE-PHEROMONES
Enders, D.,Dahmen, W.,Dederichs, E.,Weuster, P.
, p. 1235 - 1242 (2007/10/02)
A new and efficient synthesis of 1,6-dioxaspirononane-spiroacetals, starting from the simple building blocks acetone and oxiranes is described.
Determination of Relative Configurations of Spiroacetals by 1H- and 13C-NMR-Spectroscopy
Francke, Wittko,Reith, Wolfgang,Sinnwell, Volker
, p. 2686 - 2693 (2007/10/02)
The relative configuration of the spiroacetals 2, 4 - 7 and 9 - 11 is determined on the basis of solvent-depending shifts in 1H-NMR spectra and γ-effects in 13C-NMR spectra using (Z,E)-2,8-dimethyl-1,7-dioxaspiroundecane (Z,E-2) as a key-compound.
