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Enantioselective Allylation of Selected ortho ‐Substituted Benzaldehydes: A Comparative Study
Author(s) -
Hessler Filip,
Betík Robert,
Kadlčíková Aneta,
Belle Roman,
Kotora Martin
Publication year - 2014
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.201403034
Subject(s) - chemistry , synthon , enantioselective synthesis , lewis acids and bases , catalysis , brønsted–lowry acid–base theory , organic chemistry , alcohol , chiral lewis acid , lewis acid catalysis , combinatorial chemistry , medicinal chemistry
We report a systematic study of the allylation of ortho ‐substituted benzaldehydes under catalysis of a Lewis base ( N , N ‐dioxide), a Lewis acid (Keck allylation), and a Brønsted acid. ortho ‐Halobenzaldehydes were used as the aldehydic substrates, and special attention was paid to ortho ‐vinyl and alkynyl benzaldehydes, which might serve as interesting synthons for the preparation of more complex chiral compounds. Similar enantioselectivities were achieved under catalytic conditions. In the case of ortho ‐halobenzaldehydes, Lewis base catalysis proved to be more efficient, and the highest asymmetric induction for allylation of ortho ‐fluorobenzaldehyde reached 82 % ee , which is comparable to other used catalytic conditions. In cases of ortho ‐vinylbenzaldehyde, the Keck allylation provided the product in 88 % ee . An enantioenriched homoallylic alcohol was used as the starting material for the synthesis of a sertraline intermediate.