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A Brønsted Acid Catalyzed Cascade Reaction for the Conversion of Indoles to α‐(3‐Indolyl) Ketones by Using 2‐Benzyloxy Aldehydes
Author(s) -
Banerjee Ankush,
Maji Modhu Sudan
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201902268
Subject(s) - annulation , chemistry , catalysis , tryptamines , reagent , combinatorial chemistry , brønsted–lowry acid–base theory , cascade , reaction conditions , ketone , organic chemistry , chromatography , tryptamine , biochemistry
A Brønsted acid catalyzed, operationally simple, scalable route to several functionalized α‐(3‐indolyl) ketones has been developed and the long‐standing regioisomeric issue has been eliminated by choosing appropriate carbonyls. A readily available and cheap bottle reagent was used as the catalyst. This protocol was also applicable to the synthesis of densely functionalized α‐(3‐pyrrolyl) ketones. A detailed mechanistic study confirmed the involvement of enolether as a reaction intermediate. Several postsynthetic modifications along with easy access to β‐carboline, tryptamines, tryptophols, and spiro‐indolenine proclaim the synthetic utility of this powerful building block. On the basis of this concept, functionalized carbazoles were constructed by a cascade annulation strategy.