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Asymmetric Synthesis of Pyrazolone Fused Spirocyclohexeneimines via a Vinylogous Michael/Cyclization Cascade Reaction
Author(s) -
Meninno Sara,
Mazzanti Andrea,
Lattanzi Alessandra
Publication year - 2019
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201801337
Subject(s) - stereocenter , pyrazolone , pyrazolones , chemistry , cascade reaction , quaternary carbon , annulation , yield (engineering) , catalysis , michael reaction , reaction conditions , cascade , combinatorial chemistry , organic chemistry , enantioselective synthesis , materials science , chromatography , metallurgy
Diastereoisomeric pyrazolone‐fused spirocyclohexenimines, bearing contiguous all‐carbon quaternary and tertiary stereocenters, are readily synthesized for the first time in good to excellent yield (up to 98%) and high enantioselectivity (up to 97% ee) via vinylogous Michael reaction/cyclization cascade reaction of α‐arylidene pyrazolones and α,α‐dicyanoalkylidenes. The formal [4+2] atom‐economical annulation proceeds with commercially available Takemoto's catalyst under mild reaction conditions. Scale‐up reaction and post‐transformation of the products were also demonstrated.