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A Nazarov‐Ene Tandem Reaction for the Stereoselective Construction of Spiro Compounds
Author(s) -
Etling Christoph,
Tedesco Giada,
Kalesse Markus
Publication year - 2021
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.202101041
Subject(s) - ene reaction , tandem , chemistry , stereoselectivity , cascade reaction , olefin fiber , catalysis , lewis acids and bases , stereochemistry , conjugate , reactivity (psychology) , combinatorial chemistry , organic chemistry , medicine , mathematical analysis , materials science , alternative medicine , mathematics , pathology , composite material
The different reactivity of trienones under Lewis and Brønsted acids catalysis was investigated, resulting in distinct cyclization products and carbon backbones that originated either from a conjugate Prins cyclization or an interrupted Nazarov cyclization. In particular, an unprecedented Nazarov cyclization tandem reaction is presented, terminating the oxyallyl cation by an ene‐type reaction, and leading stereoselectively to bicyclic spiro compounds. The terminal olefin of this motif represents a useful handle for further functionalization, making it a strategic intermediate in total syntheses. The tandem Nazarov/ene cyclization was shown to be preferred over a Nazarov/[3+2] tandem reaction for all our substrates, independent of chain length. Deuteration studies further support the mechanistic hypothesis of the terminating ene reaction.