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Brønsted Acid‐Catalyzed Enantioselective Cycloisomerization of Arylalkynes
Author(s) -
Gicquiaud Julien,
Abadie Baptiste,
Dhara Kalyan,
Berlande Murielle,
Hermange Philippe,
Sotiropoulos JeanMarc,
Toullec Patrick Y.
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202003783
Subject(s) - cycloisomerization , enantioselective synthesis , cationic polymerization , alkyne , phenanthrenes , protonation , chemistry , brønsted–lowry acid–base theory , regioselectivity , catalysis , substituent , triple bond , organic chemistry , medicinal chemistry , double bond , phenanthrene , ion
The first example of an enantioselective carbocyclization of an alkyne‐containing substrate catalyzed by chiral Brønsted acids was achieved. The use of the 2‐hydroxynaphthyl substituent on the alkyne as a directing group constituted the key parameter enabling both efficient regioselective protonation of the carbon–carbon triple bond and chiral induction. The key cationic intermediate could be depicted either as a cationic vinylidene ortho ‐quinone methide or a stabilized vinyl cation. Atropoisomeric phenanthrenes derivatives were produced in high yields and good enantioselectivities under mild, metal‐free reaction conditions in the presence of chiral N ‐triflylphosphoramide catalysts. The carbenic nature of the cationic intermediate was also exploited to describe an example of alkyne/alkane cycloisomerization.