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Stereochemistry of the Levy Reaction
Author(s) -
Kröger Lukas,
Wünsch Bernhard
Publication year - 2018
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201801162
Subject(s) - chemistry , epimer , diastereomer , stereoselectivity , moiety , stereochemistry , enol , catalysis , organic chemistry
The one‐pot three‐component Levy reaction was used to prepare tetracyclic pyrrolo[3,4‐ b ]carbazoles 6 – 8 . cis , cis , cis ‐Configured products 6b – 8b bearing an ester moiety were isolated for the first time. Epimerization studies showed that the cis , cis , cis ‐configured diastereomers 6b – 8b are the kinetically controlled less stable products, which are formed first. The stereochemistry is nicely explained by the endo ‐stereoselectivity of the Diels–Alder reaction. High temperature, prolonged reaction times, polar solvents, bases and high concentration of acids led to epimerization at 4‐position to provide the thermodynamically favored cis , cis , trans ‐configured diastereomers 6a – 8a . It is postulated that epimerization occurred via the enol 12 or the corresponding enolate.