Formal [4 + 2] benzannulation of 2-alkenyl indoles with aldehydes: a route to structurally diverse carbazoles and bis-carbazoles

Construction of structurally diverse carbazoles and bis-carbazoles by protecting-group-free formal [4 + 2]-benzannulation of 2-alkenyl indoles and aldehydes is demonstrated. The sequence of four different reactions is executed in one-pot using readily available and cheap bottle reagents as catalysts...

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Published inOrganic & biomolecular chemistry Vol. 17; no. 7; pp. 1822 - 1826
Main Authors Banerjee, Ankush, Guin, Avishek, Saha, Shuvendu, Mondal, Anushree, Maji, Modhu Sudan
Format Journal Article
LanguageEnglish
Published England Royal Society of Chemistry 13.02.2019
Subjects
Aldehydes
Carbazoles
Catalysts
Functional groups
Indoles
NMR
Nuclear magnetic resonance
Oxygen
Reagents
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Summary:Construction of structurally diverse carbazoles and bis-carbazoles by protecting-group-free formal [4 + 2]-benzannulation of 2-alkenyl indoles and aldehydes is demonstrated. The sequence of four different reactions is executed in one-pot using readily available and cheap bottle reagents as catalysts rendering this method attractive. The incorporation of inexpensive and environmentally benign molecular oxygen as the oxidant into the final aromatization step enables tolerance of several functional groups. Construction of structurally diverse carbazoles and bis-carbazoles by protecting-group-free formal [4 + 2]-benzannulation of 2-alkenyl indoles and aldehydes is demonstrated.
Bibliography:Electronic supplementary information (ESI) available: For ESI and NMR spectra. See DOI
10.1039/c8ob02875c
ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
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ISSN:1477-0520
1477-0539
DOI:10.1039/c8ob02875c