Diethoxymethyl Protected Indoles: Synthesis and Regioselective Transformations
作者:Peter Gmeiner、Johannes Kraxner、Bernd Bollinger
DOI:10.1055/s-1996-4356
日期:1996.10
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.
Regiocontrolled Annellation Reactions Starting from Diethoxymethyl Protected Indole
作者:Johannes Kraxner、Peter Gmeiner
DOI:10.1055/s-2000-6329
日期:——
Directed metallation of the diethoxymethyl protected indole 4 followed by treatment with β-nitrostyrene leads to the 1,2-disubstituted indole 5. Using 5 as a central intermediate, the tricyclic annellation products of type 2 and 3 were accessed when the regiochemical outcome of the reactions could be controlled.