13284-97-4Relevant academic research and scientific papers
Enantio- and Diastereoselective α-Metallation of Prochiral Sulfoxides by (+)-Menthyllithium
Maercker, Adalbert,Schuhmacher, Rudolf,Buchmeier, Willi,Lutz, Heinz Dieter
, p. 2489 - 2498 (2007/10/02)
Six out of ten prochiral dialkyl sulfoxides 3 with diastereotopic α methylene protons were stereoselectively metallated by (+)-menthyllithium (11) to yield two diastereomeric pairs of enriched enantiomers 29 after the reaction with benzophenone.The maximum e.e. was 40percent.Dicyclohexyl sulfoxide (3c) was deprotonated enantioselectively with an e.e of 30percent. 2-Bornyllithium (21) was unsuccesful as a chiral base and was shown for the first time to contain 4percent of isobornyllithium (22).The reactions were performed in pentane at -80 deg C; in diethyl ether and THF the e.e's were only slightly higher, and at higher temperatures the selectivity was rapidly decreasing.It was shown that racemization takes place by an intermolecular transmetallation reaction.The structure of 29f (n = 3) was elucidated by an X-ray analysis.Key Words: (+)-Menthyllithium, stereoselective metallation with/ Prochiral sulfoxides, enantio- and diastereoselective α-deprotonation of / 2-Bornyllithium, content of isobornyllithium in / Racemization, mechanism by intermolecular transmetallation/ e.e., temperature dependence of
Iron(II)-Induced Activation of Hydroperoxides for the Dehydrogenation and Monooxygenation of Organic Substrates in Acetonitrile
Sugimoto, Hiroshi,Sawyer, Donald T.
, p. 5712 - 5716 (2007/10/02)
Solutions of Fe(II)(MeCN)4(ClO4)2 in dry acetonitrile (MeCN) catalyze the rapid disproportionation of H2O2 to O2 and H2O, but all of the catalyst remains in the Fe(II) oxidation state.In the presence of organic substrates such as 1,4-cyclohexadiene, 1,2-diphenylhydrazine, catechols, and thiols, the Fe(II)-H2O2/MeCN system yields dehydrogenated products (PhH, PhN=NPh, quinones, and RSSR) with conversion efficiencies that range from 100 percent to 17 percent.Although the Fe(II) catalyst does not promote the disproportionation of Me3COOH or m-ClC6H4C(O)OOH, these hydroperoxides are activated for the dehydrogenation of organic substrates.With substrates such as alcohols, aldehydes, methylstyrene, thioethers, sulfoxides, and phosphines, the Fe(II)(H2O2)(2+) adduct promotes their monooxygenation to aldehydes, carboxylic acids, epoxide, sulfoxides, sulfones, and phosphine oxides, respectively: Fe(II) + H2O2 -> Fe(II)(H2O2)(2+) + RH -> Fe(II) + ROH + H2O.The reaction efficiencies for the group of substrates with the Fe(II) adducts that are formed by H2O2, Me3COOH, and m-ClC6H4C(O)OOH have been evaluated.Also, the reaction rates for the substrate- dehydrogenations and monohydrogenations relative to that for Ph2SO have been determined, as have the substituent effects for the monooxygenation of 4-XC6H4CH2OH and 4-XC6H4CH(O).The Fe(II)(H2O2)(2+) adduct is an efficient catalyst for the autooxygenation of PhCH(O) to PhC(O)OOH.Mechanisms are proposed for the Fe(II)-induced activation of hydroperoxides for the dehydrogenation and monooxygenation of organic substrates.
The Solvation of Phenol by Sulphoxides in Extraction From Aqueous Solutions
Egutkin, N. L.,Malaya, I. P.,Nikitin, Yu. E.
, p. 1813 - 1815 (2007/10/02)
The solvation of phenol by sulphoxides in extraction of the former from aqueous solutions has been investigated.It has been established by the inert diluent and isomolar series methods and by dielectric measurements on the extracted phases that the extraction proceeds with formation of monosolvates.It is shown that the composition of the solvates formed is independent of temperature and the nature of the sulphoxides employed.The extraction constants and the thermodynamic functions for the partition process have been calculated.
