The unexpected conversion of a thiophene ring into a pyrrole ring via a putative nitrene intermediate

Ross Harrington; Stephen Stanforth

doi:10.1016/j.tetlet.2012.02.050

The unexpected conversion of a thiophene ring into a pyrrole ring via a putative nitrene intermediate

Ross Harrington, Stephen Stanforth

Applied Sciences Department

Research output: Contribution to journal › Article › peer-review

6 Citations (Scopus)

Abstract

Triethylphosphite induced reductive cyclisation of 1-(2-nitrophenyl)-3,5-di(2-thienyl)pyrazole 6 afforded the expected 1,3-di(2-thienyl)pyrazolo[1,2-a]benzotriazole 7 (14%) together with an unexpected product which was shown to be a 2-(2-thienyl)pyrazolo[1,5-a]pyrrolo[2,1-c]quinoxaline 8 derivative (27%). A mechanism for the extrusion of sulfur during the transformation of heterocycle 6 into product 8 is proposed.

Original language	English
Pages (from-to)	2111-2113
Journal	Tetrahedron Letters
Volume	53
Issue number	16
DOIs	https://doi.org/10.1016/j.tetlet.2012.02.050
Publication status	Published - 2012

Keywords

Heterocyclic mesomeric betaines
reductive cyclisation
nitrenes
Pyrazolo[1
2-a]benzotriazole
5-a]pyrrolo[2
1-c]quinoxaline
thiophenes
polythiophenes

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10.1016/j.tetlet.2012.02.050

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title = "The unexpected conversion of a thiophene ring into a pyrrole ring via a putative nitrene intermediate",

abstract = "Triethylphosphite induced reductive cyclisation of 1-(2-nitrophenyl)-3,5-di(2-thienyl)pyrazole 6 afforded the expected 1,3-di(2-thienyl)pyrazolo[1,2-a]benzotriazole 7 (14%) together with an unexpected product which was shown to be a 2-(2-thienyl)pyrazolo[1,5-a]pyrrolo[2,1-c]quinoxaline 8 derivative (27%). A mechanism for the extrusion of sulfur during the transformation of heterocycle 6 into product 8 is proposed.",

keywords = "Heterocyclic mesomeric betaines, reductive cyclisation, nitrenes, Pyrazolo[1, 2-a]benzotriazole, 5-a]pyrrolo[2, 1-c]quinoxaline, thiophenes, polythiophenes",

author = "Ross Harrington and Stephen Stanforth",

year = "2012",

doi = "10.1016/j.tetlet.2012.02.050",

language = "English",

volume = "53",

pages = "2111--2113",

journal = "Tetrahedron Letters",

issn = "0040-4039",

publisher = "Elsevier",

number = "16",

}

TY - JOUR

T1 - The unexpected conversion of a thiophene ring into a pyrrole ring via a putative nitrene intermediate

AU - Harrington, Ross

AU - Stanforth, Stephen

PY - 2012

Y1 - 2012

N2 - Triethylphosphite induced reductive cyclisation of 1-(2-nitrophenyl)-3,5-di(2-thienyl)pyrazole 6 afforded the expected 1,3-di(2-thienyl)pyrazolo[1,2-a]benzotriazole 7 (14%) together with an unexpected product which was shown to be a 2-(2-thienyl)pyrazolo[1,5-a]pyrrolo[2,1-c]quinoxaline 8 derivative (27%). A mechanism for the extrusion of sulfur during the transformation of heterocycle 6 into product 8 is proposed.

AB - Triethylphosphite induced reductive cyclisation of 1-(2-nitrophenyl)-3,5-di(2-thienyl)pyrazole 6 afforded the expected 1,3-di(2-thienyl)pyrazolo[1,2-a]benzotriazole 7 (14%) together with an unexpected product which was shown to be a 2-(2-thienyl)pyrazolo[1,5-a]pyrrolo[2,1-c]quinoxaline 8 derivative (27%). A mechanism for the extrusion of sulfur during the transformation of heterocycle 6 into product 8 is proposed.

KW - Heterocyclic mesomeric betaines

KW - reductive cyclisation

KW - nitrenes

KW - Pyrazolo[1

KW - 2-a]benzotriazole

KW - 5-a]pyrrolo[2

KW - 1-c]quinoxaline

KW - thiophenes

KW - polythiophenes

U2 - 10.1016/j.tetlet.2012.02.050

DO - 10.1016/j.tetlet.2012.02.050

M3 - Article

SN - 0040-4039

VL - 53

SP - 2111

EP - 2113

JO - Tetrahedron Letters

JF - Tetrahedron Letters

IS - 16

ER -

The unexpected conversion of a thiophene ring into a pyrrole ring via a putative nitrene intermediate

Abstract

Keywords

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