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Computational assessments of diastereoselective [4+2] cycloaddition and 1,3-borotopic shift of a dearomatized tertiary boronic ester intermediate: reactivities explained through transition-state distortion energies

Computational assessments of diastereoselective [4+2] cycloaddition and 1,3-borotopic shift of a dearomatized tertiary boronic ester intermediate: reactivities explained through transition-state distortion energies
Computational assessments of diastereoselective [4+2] cycloaddition and 1,3-borotopic shift of a dearomatized tertiary boronic ester intermediate: reactivities explained through transition-state distortion energies
Interception of a dearomatized tertiary boronic ester, formed through a kinetically and thermodynamically favorable 1,2-metalate rearrangement/anti-SN20 elimination of an activated ortho-lithiated benzyl amine, in a [4+2] cycloaddition or 1,3-borotopic shift has been investigated by density functional theory (DFT). Although superacitvated “naked” Li+ was found to greatly promote 1,3-borotopic shift, the diastereoselective [4+2] cycloaddition was favored. It was revealed that the factor that controls the diastereoselectivity was the steric
bulk provided by the diene, which is in agreement with experimental diastereoselectivity. A comparison of unreactive dienophiles such as maleic anhydride, diethyl maleate, and others with 4-phenyl-3H-1,2,4-triazole-
3,5(4H)-dione (PTAD) was found to be in an excellent agreement with the experiments; where their lack of reactivity is attributed to the high deformation energies of the interacting components to achieve the transition state structure which was pronounced with the high energy of LUMO orbitals.
2046-2069
23148-23155
Hussein, Aqeel
c6645ce9-c288-4b21-8af4-6f481b600bf1
Almalki, Faisal A.
41dd76fa-3ebe-4182-be58-fa4ec85f9d34
Alqahtani, Alaa M.
53bd81c9-2b3f-4ead-8500-99e603766ab4
Shityakov, Sergey
1075034a-5796-40cc-8988-f61d7a76fe01
Hussein, Aqeel
c6645ce9-c288-4b21-8af4-6f481b600bf1
Almalki, Faisal A.
41dd76fa-3ebe-4182-be58-fa4ec85f9d34
Alqahtani, Alaa M.
53bd81c9-2b3f-4ead-8500-99e603766ab4
Shityakov, Sergey
1075034a-5796-40cc-8988-f61d7a76fe01

Hussein, Aqeel, Almalki, Faisal A., Alqahtani, Alaa M. and Shityakov, Sergey (2019) Computational assessments of diastereoselective [4+2] cycloaddition and 1,3-borotopic shift of a dearomatized tertiary boronic ester intermediate: reactivities explained through transition-state distortion energies. RSC Advances, 2019 (40), 23148-23155, [9]. (doi:10.1039/c9ra03820e).

Record type: Article

Abstract

Interception of a dearomatized tertiary boronic ester, formed through a kinetically and thermodynamically favorable 1,2-metalate rearrangement/anti-SN20 elimination of an activated ortho-lithiated benzyl amine, in a [4+2] cycloaddition or 1,3-borotopic shift has been investigated by density functional theory (DFT). Although superacitvated “naked” Li+ was found to greatly promote 1,3-borotopic shift, the diastereoselective [4+2] cycloaddition was favored. It was revealed that the factor that controls the diastereoselectivity was the steric
bulk provided by the diene, which is in agreement with experimental diastereoselectivity. A comparison of unreactive dienophiles such as maleic anhydride, diethyl maleate, and others with 4-phenyl-3H-1,2,4-triazole-
3,5(4H)-dione (PTAD) was found to be in an excellent agreement with the experiments; where their lack of reactivity is attributed to the high deformation energies of the interacting components to achieve the transition state structure which was pronounced with the high energy of LUMO orbitals.

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Accepted/In Press date: 15 July 2019
e-pub ahead of print date: 26 July 2019

Identifiers

Local EPrints ID: 433008
URI: http://eprints.soton.ac.uk/id/eprint/433008
ISSN: 2046-2069
PURE UUID: 6a97ffca-9ea6-4543-a9ac-7005e4721b05

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Date deposited: 06 Aug 2019 16:30
Last modified: 03 Mar 2021 17:34

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Author: Aqeel Hussein
Author: Faisal A. Almalki
Author: Alaa M. Alqahtani
Author: Sergey Shityakov

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