2,3-Disubstituted indoles from olefins and hydrazines via tandem hydroformylation-Fischer indole synthesis and skeletal rearrangement.
The tandem hydroformylation-Fischer indolisation protocol is used in the synthesis of 2,3-disubstituted indoles. After hydroformylation of selected olefins to form alpha-branched aldehydes in a one-pot procedure these are condensed with phenylhydrazine to give hydrazones. Upon acid-promoted [3,3]-sigmatropic rearrangement indolenine intermediates with quaternary centres in the 3-position are formed, which, after selective Wagner-Meerwein-type rearrangement of one of the substituents from the 3- to the 2-position, lead to 2,3-disubstituted indoles. Several olefins, bearing substituents with various functional groups, as well as cyclic olefinic systems are investigated.
Linnepe Née Köhling
Petra
P
Fachbereich Chemie, Organische Chemie I, Universität Dortmund, Otto-Hahn-Str. 6, 44227 Dortmund, Germany.
Schmidt
Axel M
AM
Eilbracht
Peter
P
D000447:Aldehydes / Q000737:chemistry; D000475:Alkenes / Q000737:chemistry; D006834:Hydrazines / Q000737:chemistry; D006835:Hydrazones / Q000737:chemistry; D007211:Indoles / Q000138:chemical synthesis*; D010659:Phenylhydrazines / Q000737:chemistry
D000447:Aldehydes; D000475:Alkenes; D006834:Hydrazines; D006835:Hydrazones; D007211:Indoles; D010659:Phenylhydrazines; C030299:phenylhydrazine