Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles

Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles

Deprotonation of indazolium salts at low temperatures gives N-heterocyclic carbenes of indazoles (indazol-3-ylidenes) which can be trapped as rhodium complexes (X-ray analysis). In the absence of Rh, the indazol-3-ylidenes spontaneously dimerize under ring cleavage of one of the N,N-bonds and ring c...

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Main Authors: Guan, Zong, Namyslo, Jan C, Drafz, Martin H H, Nieger, Martin, Schmidt, Andreas
Format: Online
Language:English
Published: Beilstein-Institut 2014
Online Access:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3999838/
id pubmed-3999838
recordtype oai_dc
spelling pubmed-39998382014-04-28 Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles Guan, Zong Namyslo, Jan C Drafz, Martin H H Nieger, Martin Schmidt, Andreas Full Research Paper Deprotonation of indazolium salts at low temperatures gives N-heterocyclic carbenes of indazoles (indazol-3-ylidenes) which can be trapped as rhodium complexes (X-ray analysis). In the absence of Rh, the indazol-3-ylidenes spontaneously dimerize under ring cleavage of one of the N,N-bonds and ring closure to an indazole–indole spiro compound which possesses an exocyclic imine group. The E/Z isomers of the imines can be separated by column chromatography when methanol is used as eluent. We present results of a single crystal X-ray analysis of one of the E-isomers, which equilibrate in solution as well as in the solid state. Heating of the indazole–indole spiro compounds results in the formation of quinazolines by a ring-cleavage/ring-closure sequence (X-ray analysis). Results of DFT calculations are presented. Beilstein-Institut 2014-04-10 /pmc/articles/PMC3999838/ /pubmed/24778738 http://dx.doi.org/10.3762/bjoc.10.79 Text en Copyright © 2014, Guan et al; licensee Beilstein-Institut. http://www.beilstein-journals.org/bjoc This is an Open Access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The license is subject to the Beilstein Journal of Organic Chemistry terms and conditions: (http://www.beilstein-journals.org/bjoc)
repository_type Open Access Journal
institution_category Foreign Institution
institution US National Center for Biotechnology Information
building NCBI PubMed
collection Online Access
language English
format Online
author Guan, Zong
Namyslo, Jan C
Drafz, Martin H H
Nieger, Martin
Schmidt, Andreas
spellingShingle Guan, Zong
Namyslo, Jan C
Drafz, Martin H H
Nieger, Martin
Schmidt, Andreas
Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles
author_facet Guan, Zong
Namyslo, Jan C
Drafz, Martin H H
Nieger, Martin
Schmidt, Andreas
author_sort Guan, Zong
title Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles
title_short Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles
title_full Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles
title_fullStr Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles
title_full_unstemmed Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles
title_sort dimerisation, rhodium complex formation and rearrangements of n-heterocyclic carbenes of indazoles
description Deprotonation of indazolium salts at low temperatures gives N-heterocyclic carbenes of indazoles (indazol-3-ylidenes) which can be trapped as rhodium complexes (X-ray analysis). In the absence of Rh, the indazol-3-ylidenes spontaneously dimerize under ring cleavage of one of the N,N-bonds and ring closure to an indazole–indole spiro compound which possesses an exocyclic imine group. The E/Z isomers of the imines can be separated by column chromatography when methanol is used as eluent. We present results of a single crystal X-ray analysis of one of the E-isomers, which equilibrate in solution as well as in the solid state. Heating of the indazole–indole spiro compounds results in the formation of quinazolines by a ring-cleavage/ring-closure sequence (X-ray analysis). Results of DFT calculations are presented.
publisher Beilstein-Institut
publishDate 2014
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3999838/
_version_ 1612082506059743232

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