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Palladium‐Catalyzed 6‐ endo ‐Selective Oxycyclization–Alkene Addition Cascades of ortho ‐Alkynylarylcarboxamides and α,β‐Unsaturated Carbonyl Compounds
Author(s) -
Madich Youssef,
Álvarez Rosana,
Aurrecoechea José M.
Publication year - 2015
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.201500797
Subject(s) - chemistry , alkene , palladium , moiety , catalysis , ketone , heck reaction , alkyl , yield (engineering) , medicinal chemistry , organic chemistry , triple bond , double bond , materials science , metallurgy
Regio‐ and chemoselective palladium‐catalyzed cyclization–coupling cascade reactions between ortho ‐alkynylarylcarboxamides and methyl vinyl ketone or acrylaldehyde are described. An initial 6‐ endo ‐oxypalladation of the triple bond is followed by a C–C coupling to give structurally diverse isochromenimines (and related heterosubstituted derivatives), in which the α,β‐unsaturated carbonyl moiety is incorporated as an alkyl‐type exocyclic side chain. The coupling products were obtained in 76–97 % yield (average 86 % yield) without significant interference from Heck or alternative regiochemical pathways. In contrast to related cases, these cascade reactions do not require the use of protic solvents and excess amounts of halide additives, and they proceed effectively under either PdCl 2 catalysis in the presence of substoichiometric amounts of added KI or PdI 2 catalysis without any additive.