An Experimental Stereoselective Photochemical [1s,3s]-Sigmatropic Silyl Shift and the Existence of Silyl/Allyl Conical Intersections

Niels Hammer; Mette Louise Christensen; Yu Chen; Daniel Naharro; Fang Liu; Karl Anker Jørgensen; K. N. Houk

doi:10.1021/jacs.9b11579

An Experimental Stereoselective Photochemical [1s,3s]-Sigmatropic Silyl Shift and the Existence of Silyl/Allyl Conical Intersections

Niels Hammer, Mette Louise Christensen, Yu Chen, Daniel Naharro, Fang Liu^*, Karl Anker Jørgensen, K. N. Houk

^*Corresponding author for this work

Department of Chemistry

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

Abstract

We report an experimental discovery and computational investigation of the first photochemical stereoselective [1,3]-sigmatropic silyl shift of an allylsilane. An organocatalytic enantioselective cascade annulation generates a trimethylsilyl-o-isotoluene reactant in >99:1 e.r., and this trimethylsilyl-o-isotoluene contains an allylic silane moiety that undergoes a stereoselective photochemical [1,3]-silyl shift to form a benzylsilane with 96:4 e.r. The mechanism of this unprecedented [1,3]-silyl shift has been elucidated by a series of experimental studies and CASSCF, DFT, and TD-DFT calculations on model systems and the experimental system. The highly stereoselective photoreaction is proposed to occur via a singlet silyl/allyl conical intersection. This is a new demonstration of the role of conical intersections in selective photochemistry.

Original language	English
Journal	Journal of the American Chemical Society
Volume	142
Issue	13
Pages (from-to)	6030-6035
Number of pages	6
ISSN	0002-7863
DOIs	https://doi.org/10.1021/jacs.9b11579
Publication status	Published - 2020

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title = "An Experimental Stereoselective Photochemical [1s,3s]-Sigmatropic Silyl Shift and the Existence of Silyl/Allyl Conical Intersections",

abstract = "We report an experimental discovery and computational investigation of the first photochemical stereoselective [1,3]-sigmatropic silyl shift of an allylsilane. An organocatalytic enantioselective cascade annulation generates a trimethylsilyl-o-isotoluene reactant in >99:1 e.r., and this trimethylsilyl-o-isotoluene contains an allylic silane moiety that undergoes a stereoselective photochemical [1,3]-silyl shift to form a benzylsilane with 96:4 e.r. The mechanism of this unprecedented [1,3]-silyl shift has been elucidated by a series of experimental studies and CASSCF, DFT, and TD-DFT calculations on model systems and the experimental system. The highly stereoselective photoreaction is proposed to occur via a singlet silyl/allyl conical intersection. This is a new demonstration of the role of conical intersections in selective photochemistry.",

author = "Niels Hammer and Christensen, {Mette Louise} and Yu Chen and Daniel Naharro and Fang Liu and J{\o}rgensen, {Karl Anker} and Houk, {K. N.}",

year = "2020",

doi = "10.1021/jacs.9b11579",

language = "English",

volume = "142",

pages = "6030--6035",

journal = "Journal of the American Chemical Society",

issn = "0002-7863",

publisher = "ACS Publications",

number = "13",

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An Experimental Stereoselective Photochemical [1s,3s]-Sigmatropic Silyl Shift and the Existence of Silyl/Allyl Conical Intersections. / Hammer, Niels; Christensen, Mette Louise; Chen, Yu et al.
In: Journal of the American Chemical Society, Vol. 142, No. 13, 2020, p. 6030-6035.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

TY - JOUR

T1 - An Experimental Stereoselective Photochemical [1s,3s]-Sigmatropic Silyl Shift and the Existence of Silyl/Allyl Conical Intersections

AU - Hammer, Niels

AU - Christensen, Mette Louise

AU - Chen, Yu

AU - Naharro, Daniel

AU - Liu, Fang

AU - Jørgensen, Karl Anker

AU - Houk, K. N.

PY - 2020

Y1 - 2020

N2 - We report an experimental discovery and computational investigation of the first photochemical stereoselective [1,3]-sigmatropic silyl shift of an allylsilane. An organocatalytic enantioselective cascade annulation generates a trimethylsilyl-o-isotoluene reactant in >99:1 e.r., and this trimethylsilyl-o-isotoluene contains an allylic silane moiety that undergoes a stereoselective photochemical [1,3]-silyl shift to form a benzylsilane with 96:4 e.r. The mechanism of this unprecedented [1,3]-silyl shift has been elucidated by a series of experimental studies and CASSCF, DFT, and TD-DFT calculations on model systems and the experimental system. The highly stereoselective photoreaction is proposed to occur via a singlet silyl/allyl conical intersection. This is a new demonstration of the role of conical intersections in selective photochemistry.

AB - We report an experimental discovery and computational investigation of the first photochemical stereoselective [1,3]-sigmatropic silyl shift of an allylsilane. An organocatalytic enantioselective cascade annulation generates a trimethylsilyl-o-isotoluene reactant in >99:1 e.r., and this trimethylsilyl-o-isotoluene contains an allylic silane moiety that undergoes a stereoselective photochemical [1,3]-silyl shift to form a benzylsilane with 96:4 e.r. The mechanism of this unprecedented [1,3]-silyl shift has been elucidated by a series of experimental studies and CASSCF, DFT, and TD-DFT calculations on model systems and the experimental system. The highly stereoselective photoreaction is proposed to occur via a singlet silyl/allyl conical intersection. This is a new demonstration of the role of conical intersections in selective photochemistry.

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DO - 10.1021/jacs.9b11579

M3 - Journal article

C2 - 32191462

AN - SCOPUS:85082194329

SN - 0002-7863

VL - 142

SP - 6030

EP - 6035

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 13

ER -

An Experimental Stereoselective Photochemical [1s,3s]-Sigmatropic Silyl Shift and the Existence of Silyl/Allyl Conical Intersections

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