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Reversal of the Stereochemical Course of 1‐Methyl‐1 H ‐indole Addition to Cinnamaldehyde with cis ‐5‐Benzyl‐(2‐fluoromethyl)‐2,3‐dimethylimidazolidin‐4‐ones as Catalysts – a Puzzling ‘Fluorine Effect’
Author(s) -
Grošelj Uroš,
Podlipnik Črtomir,
Bezenšek Jure,
Svete Jurij,
Stanovnik Branko,
Seebach Dieter
Publication year - 2013
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.201300332
Subject(s) - chemistry , iminium , cinnamaldehyde , substituent , indole test , catalysis , nucleophilic addition , nucleophile , medicinal chemistry , stereochemistry , organic chemistry
Replacement of the cis ‐Me group by CH 2 F in the imidazolidinone organocatalyst specified in the title (so‐called McMillan generation‐I catalyst) leads to reversal of the product configuration in the title reaction. The topicity reversal in the nucleophilic addition step must arise either from cis ‐addition with respect to the benzylic substituent of an ( E )‐iminium ion intermediate or from trans ‐addition to the corresponding ( Z )‐iminium ion. Mechanistic investigations have not provided evidence for either one of these two possibilities, so far.