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The Phosphinoboration of N-Heterocycles

Lookup NU author(s): Dr Simon DohertyORCiD

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This is the authors' accepted manuscript of an article that has been published in its final definitive form by Wiley-VCH, 2017.

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Abstract

The addition of phosphinoboronate ester Ph2PBpin (pin = 1,2-O2C2Me4) (1) to a numberof different N-heterocycles has been investigated. Reaction of 1 with pyridine resulted inhighly selective formation of the corresponding 1,4-addition product, with addition of the electron-deficient Bpin group to the pyridine nitrogen atom and the phosphido group to the paracarbon atom. Conversely, reactions of para-substituted pyridine derivatives occurred predominatelyto afford 1,2-addition products while quinoline reacted to afford the 1,2-adduct whichultimately isomerized to afford the corresponding 1,4-addition product. Preliminary computationalstudies have been undertaken to explore possible pathways for these transformationsincluding transfer of the PPh2- anion from [B(PPh2)2pin]- to the 4-position of a borenium/boroniumactivated pyridine and concerted pathways for 1,2-addition via intramolecular nucleophilicattack of PPh2 at C2 of a Ph2PBpin-coordinated pyridine via a four-centered transitionstate and intramolecular transfer of PPh2 to the 2-position of a boron-activated pyridine in aphosphido-bridged dimer involving a six-centered transition state.

Publication metadata

Author(s): Geier SJ, Vogels CM, Daley EN, Decken A, Doherty S, Westcott SA

Publication type: Article

Publication status: Published

Journal: Chemistry: A European Journal

Year: 2017

Volume: 23

Issue: 58

Pages: 14485-14499

Print publication date: 17/10/2017

Online publication date: 11/08/2017

Acceptance date: 10/08/2017

Date deposited: 22/07/2017

ISSN (electronic): 1521-3765

Publisher: Wiley-VCH

URL: https://doi.org/10.1002/chem.201702203

DOI: 10.1002/chem.201702203

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