13921-09-0Relevant articles and documents
Base-Mediated Radical Borylation of Alkyl Sulfones
Huang, Mingming,Hu, Jiefeng,Krummenacher, Ivo,Friedrich, Alexandra,Braunschweig, Holger,Westcott, Stephen A.,Radius, Udo,Marder, Todd B.
supporting information, (2021/12/02)
A practical and direct method was developed for the production of versatile alkyl boronate esters via transition metal-free borylation of primary and secondary alkyl sulfones. The key to the success of the strategy is the use of bis(neopentyl glycolato) diboron (B2neop2), with a stoichiometric amount of base as a promoter. The practicality and industrial potential of this protocol are highlighted by its wide functional group tolerance, the late-stage modification of complex compounds, no need for further transesterification, and operational simplicity. Radical clock, radical trap experiments, and EPR studies were conducted which show that the borylation process involves radical intermediates.
Transalkylation of alkyl aryl sulfides with alkylating agents
Nawrot, Daria,Koleni?, Marek,Kune?, Ji?í,Kostelansky, Filip,Miletin, Miroslav,Novakova, Veronika,Zimcik, Petr
, p. 594 - 599 (2018/01/01)
The reaction of methyl iodide with tert-butylphenylsulfide in DMF leads to a transalkylation that produces methylphenylsulfide. This transalkylation reaction was further studied by 1H NMR spectroscopy. The polarity of the solvent, the electron density on the sulfur atom, and the strength of the alkylating agent (MeI, EtI, BuI, dimethyl sulfate, or dimethyl carbonate) played important roles in the reaction. The suggested mechanism of the reaction involves the formation of a dialkyl aryl sulfonium salt that subsequently eliminates the radical. This mechanism was supported by the observation of higher conversion rates for compounds with more branched alkyl groups on the sulfur atom, which may lead to the formation of more stable radicals.
Experimental and theoretical investigation of the enantiomerization of Lithium α-tert-butylsulfonyl carbanion salts and the determination of their structures in solution and in the crystal
Scholz, Roland,Hellmann, Gunther,Rohs, Susanne,Raabe, Gerhard,Runsink, Jan,Oezdemir, Diana,Luche, Olaf,Hess, Thomas,Giesen, Alexander W.,Atodiresei, Juliana,Lindner, Hans J.,Gais, Hans-Joachim
supporting information; experimental part, p. 4559 - 4587 (2010/10/19)
Dynamic NMR (DNMR) spectroscopy of [R1C(R2)SO 2R3]Li (R1, R2 = alkyl, phenyl; R3 = Ph, tBu, adamantyl, CEt3) in [D8]THF has shown that the S-tBu, S-adamantyl, and S-CEt3 derivatives have a significantly higher enantiomerization barrier than their S-Ph analogues. C α-S bond rotation is most likely the rate-determining step of the enantiomerization of the salts bearing a bulky group at the S atom and two substituents at the Cα atom. Ab initio calculations on [Me(Ph)- SO 2tBu]- gave information about the two Cα-S rotational barriers, which are dominated by steric effects. Cryoscopy of [R1C(R 2)SO2tBu]Li in THF at -108°C revealed the existence of monomers and dimers. X-ray crystal structure analysis of the monomers and dimers of [R1C(R2)SO2tBu]Li·L n (R1 = Me, Et, tBuCH2, PhCH2, tBu; R2 = Ph, L = THF, 12-crown-4, PMDTA) and [R1C(R 2)SO2Ph]Li·2diglyme [R1 = R2 = Me, Et; R1-R2 = (CH2)5] showed them to be O-Li contact ion pairs (CIPs). The monomers and dimers have a Cα-S conformation in which the lone-pair orbital at the Cα atom bisects the O-S-O angle and a significantly shortened Cα-S bond. The Cα atom of [R1C(R2)SO2R 3]Li·Ln (R1 = Ph; R3 = Ph, tBu) is planar, whereas the Cα atom of [R1C(R 2)SO2R3]Li·Ln (R1 = R2 = alkyl) is strongly pyramidalized in the case of R3 = Ph and most likely planar for R3 = tBu. Ab initio calculations on [MeC- (Me)SO2R]- gave a pyramidalized Cα atom for R = Me and a nearly planar one for R = CF3 and tBu. The [R1C(R 2)SO2-tBu]Li salts were characterized by 1H, 13C, and 6Li NMR spectroscopy. 1H{ 1H} and 6Li{1H} NOE experiments are in accordance with the existence of O-Li CIPs. 1H and 13C NMR spectroscopy of [R1C(R2)SO2tBu]Li in [D 8]THF at low temperatures showed equilibrium mixtures of up to five different species being most likely monomeric and dimeric O-Li CIPs with different configurations. According to 7Li NMR spectroscopy, the addition of HMPA to [MeC(Ph)SO2tBu]Li in [D8]THF at low temperatures causes the formation of the separated ion pair [MeC(Ph)SO 2tBu]Li(HMPA)4.
