Mechanistic insights into the triazolylidene-catalysed Stetter and benzoin reactions: role of the N-aryl substituent

Christopher J. Collett; Richard S. Massey; Oliver R. Maguire; Andrei S. Batsanov; AnnMarie C. O'Donoghue; Andrew D. Smith

doi:10.1039/c2sc22137c

Mechanistic insights into the triazolylidene-catalysed Stetter and benzoin reactions: role of the N-aryl substituent

Christopher J. Collett, Richard S. Massey, Oliver R. Maguire, Andrei S. Batsanov, AnnMarie C. O'Donoghue^*, Andrew D. Smith

^*Corresponding author for this work

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Abstract

The in situ observation, isolation and reversible formation of intermediate 3-(hydroxybenzyl) azolium salts derived from NHC addition to a range of substituted benzaldehydes is probed. Equilibrium constants for the formation of these 3-(hydroxybenzyl) azolium salts, as well as rate constants of hydrogen-deuterium exchange (k(ex)) at C(alpha) of these intermediates for a range of N-aryl triazolinylidenes is reported. These combined studies give insight into the preference of N-pentafluorophenyl NHCs to participate in benzoin and Stetter reaction processes.

Original language	English
Pages (from-to)	1514-1522
Number of pages	9
Journal	Chemical Science
Volume	4
Issue number	4
Early online date	4 Jan 2013
DOIs	https://doi.org/10.1039/c2sc22137c
Publication status	Published - 2013

Keywords

Heterocyclic carbene
Thiazolium salts
Michael addition
Triazolium salts
Umpolung reaction
Nucleophilic carbenes
Breslow intermediate
Alpha,beta-unsaturated aldehydes
Thiamine action
Homoenolate equivalents

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10.1039/c2sc22137c

Collett2013ChemSci c2sc22137c
This is an open access article. This journal is (c) The Royal Society of Chemistry 2013
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title = "Mechanistic insights into the triazolylidene-catalysed Stetter and benzoin reactions: role of the N-aryl substituent",

abstract = "The in situ observation, isolation and reversible formation of intermediate 3-(hydroxybenzyl) azolium salts derived from NHC addition to a range of substituted benzaldehydes is probed. Equilibrium constants for the formation of these 3-(hydroxybenzyl) azolium salts, as well as rate constants of hydrogen-deuterium exchange (k(ex)) at C(alpha) of these intermediates for a range of N-aryl triazolinylidenes is reported. These combined studies give insight into the preference of N-pentafluorophenyl NHCs to participate in benzoin and Stetter reaction processes.",

keywords = "Heterocyclic carbene, Thiazolium salts, Michael addition, Triazolium salts, Umpolung reaction, Nucleophilic carbenes, Breslow intermediate, Alpha,beta-unsaturated aldehydes, Thiamine action, Homoenolate equivalents",

author = "Collett, {Christopher J.} and Massey, {Richard S.} and Maguire, {Oliver R.} and Batsanov, {Andrei S.} and O'Donoghue, {AnnMarie C.} and Smith, {Andrew D.}",

year = "2013",

doi = "10.1039/c2sc22137c",

language = "English",

volume = "4",

pages = "1514--1522",

journal = "Chemical Science",

issn = "2041-6520",

publisher = "Royal Society of Chemistry",

number = "4",

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T1 - Mechanistic insights into the triazolylidene-catalysed Stetter and benzoin reactions

T2 - role of the N-aryl substituent

AU - Collett, Christopher J.

AU - Massey, Richard S.

AU - Maguire, Oliver R.

AU - Batsanov, Andrei S.

AU - O'Donoghue, AnnMarie C.

AU - Smith, Andrew D.

PY - 2013

Y1 - 2013

N2 - The in situ observation, isolation and reversible formation of intermediate 3-(hydroxybenzyl) azolium salts derived from NHC addition to a range of substituted benzaldehydes is probed. Equilibrium constants for the formation of these 3-(hydroxybenzyl) azolium salts, as well as rate constants of hydrogen-deuterium exchange (k(ex)) at C(alpha) of these intermediates for a range of N-aryl triazolinylidenes is reported. These combined studies give insight into the preference of N-pentafluorophenyl NHCs to participate in benzoin and Stetter reaction processes.

AB - The in situ observation, isolation and reversible formation of intermediate 3-(hydroxybenzyl) azolium salts derived from NHC addition to a range of substituted benzaldehydes is probed. Equilibrium constants for the formation of these 3-(hydroxybenzyl) azolium salts, as well as rate constants of hydrogen-deuterium exchange (k(ex)) at C(alpha) of these intermediates for a range of N-aryl triazolinylidenes is reported. These combined studies give insight into the preference of N-pentafluorophenyl NHCs to participate in benzoin and Stetter reaction processes.

KW - Heterocyclic carbene

KW - Thiazolium salts

KW - Michael addition

KW - Triazolium salts

KW - Umpolung reaction

KW - Nucleophilic carbenes

KW - Breslow intermediate

KW - Alpha,beta-unsaturated aldehydes

KW - Thiamine action

KW - Homoenolate equivalents

U2 - 10.1039/c2sc22137c

DO - 10.1039/c2sc22137c

M3 - Article

SN - 2041-6520

VL - 4

SP - 1514

EP - 1522

JO - Chemical Science

JF - Chemical Science

IS - 4

ER -

Mechanistic insights into the triazolylidene-catalysed Stetter and benzoin reactions: role of the N-aryl substituent

Abstract

Keywords

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