89358-22-5Relevant academic research and scientific papers
Concerning the deprotonation of the trimethylsulfonium ion by the dimethylsulfinyl anion
Haiss, Peter,Zeller, Klaus-Peter
experimental part, p. 7748 - 7754 (2011/12/03)
As shown by deuterium labelling experiments, the deprotonation of the trimethylsulfonium ion (1) by the dimsyl anion (8) is accompanied by extensive hydrogen exchange. This cannot be explained by an acid-base equilibrium between the trimethylsulfonium ion (1) and the dimsyl anion (8) on one side and dimethylsulfonium methylide (2) and DMSO on the other side, because for thermodynamic reasons this process is irreversible due to the limited life-time of 2. Therefore, the isotopic exchange that accompanies the deprotonation is an indicator of a more complex deprotonation process. It is suggested that in a kinetically controlled reaction, a proton of 1 is transferred to the O-atom of 8 rather than to the carbanionic centre. This means that instead of DMSO, its tautomer, hydroxy-methylsulfonium methylide (10), is obtained in the deprotonation process. Similarly, in the acid-base interaction between DMSO and its conjugate base 8, the formation of the DMSO tautomer 10 is kinetically favoured. The intermediate 10 produced in this way transfers a DMSO-derived proton to 1 when it intervenes in the back reaction 10 + 2 → 8 + 1. An alternative mechanism based on methyl group exchange between 1 and 8 could be excluded by a 13C-labelling experiment. The hydrogen exchange according to the suggested scenario is taking place in competition with the reaction of dimethylsulfonium methylide (2) with electrophilic substrates. This explains the different degrees of isotopic exchange when compounds of different electrophilicities are used to scavenge 2 from the deprotonation-hydrogen distribution equilibria.
CHLOROMETHYL-LITHIUM AND 1-CHLORO-2-METHYLPROP-1-ENYL-LITHIUM: USEFUL INTERMEDIATES IN THE SYNTHESIS OF UNSATURATED AND BIFUNCTIONALIZED COMPOUNDS
Barluenga, Jose,Fernandez-Simon, Jose L.,Concellon, Jose M.,Yus, Miguel
, p. 3339 - 3344 (2007/10/02)
The reaction of in situ generated chloromethyl-lithium with ketones (5) at -78 deg C afforded, after lithiation with lithium naphthalenide at the same temperature, β-oxidoalkyl-lithium compounds (6), which on reaction with electrophiles (deuterium oxide, dimethyl disulphide, carbon dioxide, cyclohexanone, and allyl bromide) yielded bifunctionalized compounds (7).When the lithiation step was carried out with lithium powder and at temperatures ranging between -60 deg C and 20 deg C, the corresponding decomposition of intermediates (6) derived from aldehydes and ketones (5) took place spontaneously giving the corresponding terminal or exocyclic olefins (11) regioselectively.The use of in situ generated 1-chloro-2-methylprop-1-enyl-lithium as organolithium reagent in the addition to carbonyl compounds (5) at -110 deg C, followed by transformation of the resulting chlorohydrin (13) into the corresponding methyl ether (14) (successive treatment with sodium hydride and methyl iodide at 0-20 deg C) gave, after lithiation with lithium phenanthrenide at room temperature, the corresponding substituted cumulenes (12).
β-Oxidofunctionalized Organolithium Intermediates from Ketones: A Simple New Access
Barluenga, Jose,Fernandez-Simon, Jose L.,Concellon, Jose M.,Yus, Miguel
, p. 915 - 916 (2007/10/02)
Chloromethyl-lithium generated in situ, reacts at -78 deg C with ketones (5) to afford, after lithiation with lithium naphthalenide, β-oxidoalkyl-lithium compounds (1), which on reaction with electrophiles (deuterium oxide, dimethyl disulphide, carbon dioxide, cyclohexanone, and allyl bromide) yield bifunctionalized compounds (6).
β-Substituted Organolithium Compounds from Chlorohydrins: Application to the Direct Synthesis of Bifunctionalized Organic Cpmpounds
Barluenga, Jose,Florez, Josefa,Yus, Miguel
, p. 3019 - 3026 (2007/10/02)
The reaction of different chlorohydrins with n-butyl-lithium at -78 deg C followed by metallation wiht lithium naphthalenide at the same temperature leads to very reactive organolithium compounds bearing an alkoxide function at the β-position with respect to metal.The reaction of these intermediates with several electriphiles leads to mono- as well as bi-functionalized organic compounds.Thus, treatment of these dianions with deuterium oxide, oxygen, carbon dioxide, benzyl bromide, dimethyl disulphide, and carbonyl compounds, gave 2-deuterioalcohols, 1,2-diols, β-hydroxy-acids, 2-benzyl alcohols, 2-hydroxy-thioethers, and 1,3-diols respectively.The preparation of β-substituted organolithium derivatives can be alternatively carried out starting from α-chloroketones by the same procedure.When the lithium atom is linked to a secondary carbon atom the dianions are very unstable and decompose, even at -100 deg C, by β-elimination yielding the corresponding olefins.
