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Chiral Unsymmetrically Substituted Bipyridine N , N′ ‐Dioxides as Catalysts for the Allylation of Aldehydes
Author(s) -
Ulč Jan,
Nečas David,
Koukal Petr,
Havlíček Vojtěch,
Tošner Zdeněk,
Hybelbauerová Simona,
Kotora Martin
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.201800485
Subject(s) - chemistry , catalysis , cinnamaldehyde , moiety , medicinal chemistry , aryl , bipyridine , organic chemistry , crystal structure , alkyl
A series of unsymmetrically substituted diastereoisomeric ( R a ,R ) and ( S a ,R ) bipyridine N , N′ ‐dioxides was synthesized by using oxidative coupling of the corresponding metallated tetrahydroisoquinoline N ‐oxides in the presence of iodine. The N , N′ ‐dioxides contained substituted aryl groups with electron‐donating or electron‐accepting groups in the near vicinity of the N , N′ ‐dioxide moiety. Their catalytic activity was tested in a series of reactions of allyltrichlorosilane with various substituted benzaldehydes, thiophenecarbaldehyde, and cinnamaldehyde. The reactions proceeded with high enantioselectivities (up to 98 % ee ) with catalyst loadings as low as 0.5 mol‐%. Furthermore, allylation reactions of ( E )‐3‐iodomethacrylaldehyde were also carried out to give chiral ( E )‐1‐iodo‐2‐methylpenta‐1,4‐dien‐3‐ol, a convenient building block for the synthesis of natural products. The allylations proceeded with high enantioselectivities (up to ca. 99 % ee ) with a catalyst loading of 2.5 mol‐%.