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Palladium-Catalysed Syntheses of 3-Substituted Indoles and Hetero Analogues

Wensbo, David (1996)
Abstract
3-Substituted indoles and their analogues - hetero condensed pyrroles (hetero-indoles) - have been synthesised by two different palladium-catalysed reactions:



a) A series of 2-silylated 3-substituted (hetero-)indoles have been prepared by palladium-catalysed coupling between o-iodo(het)arylamines and silyl substituted internal acetylenes. The outcome of the reaction was found to depend on the type of silyl substituent (tert-butyl dimethylsilyl or trimethylsilyl) employed. Tryptophan derivatives were obtained by desilylation of the corresponding 2-silylated indoles. Attempted desilylation of 2-silylated 3-hydroxymethyl-hetero-indoles resulted in a ring opening reaction of the pyrrole moiety.



b) A series... (More)
3-Substituted indoles and their analogues - hetero condensed pyrroles (hetero-indoles) - have been synthesised by two different palladium-catalysed reactions:



a) A series of 2-silylated 3-substituted (hetero-)indoles have been prepared by palladium-catalysed coupling between o-iodo(het)arylamines and silyl substituted internal acetylenes. The outcome of the reaction was found to depend on the type of silyl substituent (tert-butyl dimethylsilyl or trimethylsilyl) employed. Tryptophan derivatives were obtained by desilylation of the corresponding 2-silylated indoles. Attempted desilylation of 2-silylated 3-hydroxymethyl-hetero-indoles resulted in a ring opening reaction of the pyrrole moiety.



b) A series of 3-substituted (hetero-)indoles have been prepared by N-allylation of N-(tert-butoxycarbonyl)-o-iodo(het)arylamines, followed by palladium-catalysed ring closure in a one pot reaction. (Hetero-)indole-3-acetic acid derivatives and (thia-)indole-3-pyruvic acid oxime ethers were thus obtained by employment of ethyl 4-bromocrotonate and the oxime ethers of ethyl (E)-2-oxo-5-bromo-3-pentenoate as N-allylating agents, respectively. Racemic thia-tryptophans were obtained by reduction of the oxime ether function in the corresponding thia-indole-3-pyruvic acid oxime ethers.



A novel method, involving treatment of the substrate with silica gel at low pressure, was discovered for the selective removal of N-BOC substituents (BOC=tert-butoxycarbonyl). (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Doc Andersson, Pehr, Uppsala University
publishing date
type
Thesis
publication status
published
subject
keywords
Organic chemistry, Organisk kemi
pages
58 pages
publisher
Organic Chemistry, Lund University
defense location
Chemical Center (G)
defense date
1996-10-24 10:15
external identifiers
  • Other:ISRN: LUNDL/NKOK-1034-SE
language
English
LU publication?
no
id
888f07be-2193-41ec-9ec4-bac4e6cc2a31 (old id 28663)
date added to LUP
2007-06-12 09:18:49
date last changed
2016-09-19 08:45:04
@phdthesis{888f07be-2193-41ec-9ec4-bac4e6cc2a31,
  abstract     = {3-Substituted indoles and their analogues - hetero condensed pyrroles (hetero-indoles) - have been synthesised by two different palladium-catalysed reactions:<br/><br>
<br/><br>
a) A series of 2-silylated 3-substituted (hetero-)indoles have been prepared by palladium-catalysed coupling between o-iodo(het)arylamines and silyl substituted internal acetylenes. The outcome of the reaction was found to depend on the type of silyl substituent (tert-butyl dimethylsilyl or trimethylsilyl) employed. Tryptophan derivatives were obtained by desilylation of the corresponding 2-silylated indoles. Attempted desilylation of 2-silylated 3-hydroxymethyl-hetero-indoles resulted in a ring opening reaction of the pyrrole moiety.<br/><br>
<br/><br>
b) A series of 3-substituted (hetero-)indoles have been prepared by N-allylation of N-(tert-butoxycarbonyl)-o-iodo(het)arylamines, followed by palladium-catalysed ring closure in a one pot reaction. (Hetero-)indole-3-acetic acid derivatives and (thia-)indole-3-pyruvic acid oxime ethers were thus obtained by employment of ethyl 4-bromocrotonate and the oxime ethers of ethyl (E)-2-oxo-5-bromo-3-pentenoate as N-allylating agents, respectively. Racemic thia-tryptophans were obtained by reduction of the oxime ether function in the corresponding thia-indole-3-pyruvic acid oxime ethers.<br/><br>
<br/><br>
A novel method, involving treatment of the substrate with silica gel at low pressure, was discovered for the selective removal of N-BOC substituents (BOC=tert-butoxycarbonyl).},
  author       = {Wensbo, David},
  keyword      = {Organic chemistry,Organisk kemi},
  language     = {eng},
  pages        = {58},
  publisher    = {Organic Chemistry, Lund University},
  title        = {Palladium-Catalysed Syntheses of 3-Substituted Indoles and Hetero Analogues},
  year         = {1996},
}