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The Use of (-)-Sparteine/Organolithium Reagents for the Enantioselective Lithiation of 7,8-Dipropyltetrathia[7]helicene: Single and Double Kinetic Resolution Procedures

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The Use of (-)-Sparteine/Organolithium Reagents for the Enantioselective Lithiation of 7,8-Dipropyltetrathia[7]helicene: Single and Double Kinetic Resolution Procedures. / Doulcet, Julien; Stephenson, G. Richard.
In: Chemistry - A European Journal, Vol. 21, No. 51, 14.12.2015, p. 18677-18689.

Research output: Contribution to Journal/Magazine › Journal article › peer-review

Harvard

Doulcet, J & Stephenson, GR 2015, 'The Use of (-)-Sparteine/Organolithium Reagents for the Enantioselective Lithiation of 7,8-Dipropyltetrathia[7]helicene: Single and Double Kinetic Resolution Procedures', Chemistry - A European Journal, vol. 21, no. 51, pp. 18677-18689. https://doi.org/10.1002/chem.201502958

APA

Doulcet, J., & Stephenson, G. R. (2015). The Use of (-)-Sparteine/Organolithium Reagents for the Enantioselective Lithiation of 7,8-Dipropyltetrathia[7]helicene: Single and Double Kinetic Resolution Procedures. Chemistry - A European Journal, 21(51), 18677-18689. https://doi.org/10.1002/chem.201502958

Vancouver

Doulcet J, Stephenson GR. The Use of (-)-Sparteine/Organolithium Reagents for the Enantioselective Lithiation of 7,8-Dipropyltetrathia[7]helicene: Single and Double Kinetic Resolution Procedures. Chemistry - A European Journal. 2015 Dec 14;21(51):18677-18689. Epub 2015 Dec 4. doi: 10.1002/chem.201502958

Author

Doulcet, Julien ; Stephenson, G. Richard. / The Use of (-)-Sparteine/Organolithium Reagents for the Enantioselective Lithiation of 7,8-Dipropyltetrathia[7]helicene : Single and Double Kinetic Resolution Procedures. In: Chemistry - A European Journal. 2015 ; Vol. 21, No. 51. pp. 18677-18689.

Bibtex

@article{5c6f8abbce68499ab4b9c3658e3cb831,
title = "The Use of (-)-Sparteine/Organolithium Reagents for the Enantioselective Lithiation of 7,8-Dipropyltetrathia[7]helicene: Single and Double Kinetic Resolution Procedures",
abstract = "The effect of organolithium reagent (RLi: R=nBu, iPr, sBu, tBu), solvent (diethyl ether, diethyl ether/THF and MTBE), and stoichiometry on the (-)-sparteine-mediated silylation of 7,8-dipropyltetrathia[7]helicene shows that, unusually, substantially more than 0.5 equivalent of RLi (R=iPr, sBu, tBu) and a large excess of (-)-sparteine (R=nBu, sBu) is often needed to achieve substantial conversions and good ee values. With nBuLi, however, just one equivalent of the organolithium reagent is sufficient to obtain high conversions. Our best results were obtained using the convenient tBuLi/(-)-sparteine adduct with which the need for a high (-)-sparteine/RLi ratio can be avoided. Single- and double-kinetic resolution (KR) procedures give enantiopure samples of 2-trimethylsilyl- and 2,13-di(trimethylsilyl)-7,8-dipropyltetrathia[7]helicene and two-step double-KR combining (-)-sparteine/sBuLi and chiral formamides affords the synthetically valuable 2-formyl-7,8-dipropyltetrathia[7]helicene. This is the first use of (-)-sparteine for the enantioselective lithiation of helicenes and the first report of tBuLi outperforming sBuLi in a (-)-sparteine-mediated procedure.",
keywords = "(-)-sparteine-mediated lithiation, asymmetric synthesis, double-KR, kinetic resolution, tetrathia[7]helicenes",
author = "Julien Doulcet and Stephenson, {G. Richard}",
note = "Publisher Copyright: {\textcopyright} 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.",
year = "2015",
month = dec,
day = "14",
doi = "10.1002/chem.201502958",
language = "English",
volume = "21",
pages = "18677--18689",
journal = "Chemistry - A European Journal",
issn = "0947-6539",
publisher = "Wiley-VCH Verlag",
number = "51",

}

RIS

TY - JOUR

T1 - The Use of (-)-Sparteine/Organolithium Reagents for the Enantioselective Lithiation of 7,8-Dipropyltetrathia[7]helicene

T2 - Single and Double Kinetic Resolution Procedures

AU - Doulcet, Julien

AU - Stephenson, G. Richard

N1 - Publisher Copyright: © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PY - 2015/12/14

Y1 - 2015/12/14

N2 - The effect of organolithium reagent (RLi: R=nBu, iPr, sBu, tBu), solvent (diethyl ether, diethyl ether/THF and MTBE), and stoichiometry on the (-)-sparteine-mediated silylation of 7,8-dipropyltetrathia[7]helicene shows that, unusually, substantially more than 0.5 equivalent of RLi (R=iPr, sBu, tBu) and a large excess of (-)-sparteine (R=nBu, sBu) is often needed to achieve substantial conversions and good ee values. With nBuLi, however, just one equivalent of the organolithium reagent is sufficient to obtain high conversions. Our best results were obtained using the convenient tBuLi/(-)-sparteine adduct with which the need for a high (-)-sparteine/RLi ratio can be avoided. Single- and double-kinetic resolution (KR) procedures give enantiopure samples of 2-trimethylsilyl- and 2,13-di(trimethylsilyl)-7,8-dipropyltetrathia[7]helicene and two-step double-KR combining (-)-sparteine/sBuLi and chiral formamides affords the synthetically valuable 2-formyl-7,8-dipropyltetrathia[7]helicene. This is the first use of (-)-sparteine for the enantioselective lithiation of helicenes and the first report of tBuLi outperforming sBuLi in a (-)-sparteine-mediated procedure.

AB - The effect of organolithium reagent (RLi: R=nBu, iPr, sBu, tBu), solvent (diethyl ether, diethyl ether/THF and MTBE), and stoichiometry on the (-)-sparteine-mediated silylation of 7,8-dipropyltetrathia[7]helicene shows that, unusually, substantially more than 0.5 equivalent of RLi (R=iPr, sBu, tBu) and a large excess of (-)-sparteine (R=nBu, sBu) is often needed to achieve substantial conversions and good ee values. With nBuLi, however, just one equivalent of the organolithium reagent is sufficient to obtain high conversions. Our best results were obtained using the convenient tBuLi/(-)-sparteine adduct with which the need for a high (-)-sparteine/RLi ratio can be avoided. Single- and double-kinetic resolution (KR) procedures give enantiopure samples of 2-trimethylsilyl- and 2,13-di(trimethylsilyl)-7,8-dipropyltetrathia[7]helicene and two-step double-KR combining (-)-sparteine/sBuLi and chiral formamides affords the synthetically valuable 2-formyl-7,8-dipropyltetrathia[7]helicene. This is the first use of (-)-sparteine for the enantioselective lithiation of helicenes and the first report of tBuLi outperforming sBuLi in a (-)-sparteine-mediated procedure.

KW - (-)-sparteine-mediated lithiation

KW - asymmetric synthesis

KW - double-KR

KW - kinetic resolution

KW - tetrathia[7]helicenes

U2 - 10.1002/chem.201502958

DO - 10.1002/chem.201502958

M3 - Journal article

C2 - 25205455

AN - SCOPUS:84954349372

VL - 21

SP - 18677

EP - 18689

JO - Chemistry - A European Journal

JF - Chemistry - A European Journal

SN - 0947-6539

IS - 51

ER -