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Hydroxy Compounds (hydroxy + compound)
Selected AbstractsThe First Simple Method of Protection of Hydroxy Compounds as Their O-Boc Derivatives under Lewis Acid Catalysis.CHEMINFORM, Issue 49 2006Giuseppe Bartoli Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] ,-Carbonyl Substituent Effect on the Lifetimes of Triplet 1,4-Biradicals from Norrish-Type-II ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2006Xichen Cai Dr. Abstract Triplet 1,4-biradicals were generated by Norrish-Type-II hydrogen transfer from ,-heteroatom-substituted ,-branched butyrophenones 1,6 and detected by laser flash absorption measurements. For three oxy-substituted compounds 2,4 (R,=OH, OCOMe, OCOOEt) comparable lifetimes were determined in acetonitrile (roughly 1.5 ,s). In benzene, divergent trends were observed: for the hydroxy compound 2 a lower lifetime of 790 ns was determined, whereas for 3 and 4 the lifetimes increased to 4.9 ,s. Photolyses of the ,-amino-substituted compounds 1 and 6 resulted in transient species with significant lower lifetimes (for 1 160 ns in benzene and 450 ns in acetonitrile; for 6 <100 ns in both solvents). The mesyloxy substrate 5 undergoes rapid CO bond cleavage upon photolysis and no transient triplet species were detected. Computational (UB3,LYP/6,31G* and natural don orbital (NBO) analyses) results supported the assumption of a negative hyperconjugative interaction strongly stabilizing ,-oxy-substituted over ,-amino-substituted radicals. [source] Synthesis of Pyrrole Derivatives through Functionalization of 3,4-Bis(lithiomethyl)dihydropyrrolesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2003José Barluenga Abstract Bis(2-lithioallyl)amines 2, substituted at the double bonds, undergo intramolecular carbolithiation of a lithiated double bond in different solvents to afford dilithiated dihydropyrroles 3. Treatment of these dianions with electrophiles allows the preparation of functionalized pyrrole derivatives 5 and 6. Interestingly, treatment of these dianions with carboxylic esters selectively affords either keto or hydroxy compounds (9 or 10), depending on the conditions. Several experiments have been carried out in order to clarify the mechanism of this selective transformation. Finally, dilithiated dihydropyrrole 3a could be transformed in a three-step procedure into the corresponding 3,4-bis(bromomethyl) derivative 31, which can easily be converted into bicyclic pyrrole compounds 32,33 by treatment with different nucleophiles. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Crystallization and preliminary crystallographic analysis of Gre2p, an NADP+ -dependent alcohol dehydrogenase from Saccharomyces cerevisiaeACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 7 2010Klaus Breicha Gre2p [Genes de respuesta a estres (stress-response gene)] from Saccharomyces cerevisiae is a monomeric enzyme of 342 amino acids with a molecular weight of 38.1,kDa. The enzyme catalyses both the stereospecific reduction of keto compounds and the oxidation of various hydroxy compounds and alcohols by the simultaneous consumption of the cofactor NADPH and formation of NADP+. Crystals of a Gre2p complex with NADP+ were grown using PEG 8000 as a precipitant. They belong to the monoclinic space group P21. The current diffraction resolution is 3.2,Å. In spite of the monomeric nature of Gre2p in solution, packing and self-rotation calculations revealed the existence of two Gre2p protomers per asymmetric unit related by a twofold noncrystallographic axis. [source] | ||||||||||