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Synthesis 1996; 1996(10): 1196-1198
DOI: 10.1055/s-1996-4356
short paper
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Diethoxymethyl Protected Indoles: Synthesis and Regioselective Transformations

Peter Gmeiner* , Johannes Kraxner, Bernd Bollinger
  • *Pharmazeutisches Institut der Universität Bonn, An der Immenburg 4, D-53121 Bonn, Germany, Fax +49(228)737929
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Publication Date:
31 December 2000 (online)

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Reaction of the indoles 1a-d with triethyl orthoformate gives access to the N-diethoxymethyl derivatives 2a-d. Convenient and mild removal of the diethoxymethyl substituent is possible by subsequent treatment of 2a-d with aqueous HCl and NaOH. Using 2a as an example, it could be shown that deprotonation followed by addition of an electrophile (Me3SiCl or Bu3SnCl) leads to substitution in position 2. Further functionalization was possible by palladium-catalyzed coupling reactions starting from the stannane 4. The diethoxymethyl protected η 6-tricarbonylchromium complex 5 facilitated acylation in position 2 after deprotonation.

Synthesis and selective functionalization of diethoxymethyl (DEM) protected indoles are reported.