Brønsted Acid‐Catalyzed Enantioselective Cycloisomerization of Arylalkynes. Issue 69 (17th November 2020)

• Record Type: Journal Article
• Authors: Gicquiaud, Julien; Abadie, Baptiste; Dhara, Kalyan; Berlande, Murielle; Hermange, Philippe; Sotiropoulos, Jean‐Marc; Toullec, Patrick Y.
• Is Part Of: Chemistry. Volume 26:Issue 69(2020)
• Page Start: 16266
• Page End: 16271
• Publication Date: 2020-11-17
• Subjects: alkyne -- asymmetric catalysis -- atropoisomer -- Brønsted acid -- cycloisomerization; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202003783
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: 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. Abstract : Chiral N ‐triflyl phosphoramides catalyze the asymmetric carbocyclization of alkynyl aryl substrates. The introduction of a 2‐naphtolyl substituent on the alkyne enables the chemo‐ and regioselective protonation of alkynes and delivers atropisomeric phenanthrenes and dihydronaphtalenes enantioselectively.