Enantioselective Au(i)-catalyzed tandem reactions between 2-alkynyl enones and naphthols by the tethered counterion-directed catalysis strategy

Abstract

The enantioselective tandem cycloisomerization / addition reactions of 2-alkynyl enones with 1- and 2-naphthols have been investigated using gold(I) catalysts featuring hybrid phosphine-phosphoric acid chiral ligands, according to the Tethered...

Insights into the Enantioselective Au(I)‐Catalyzed Reactions between 2‐Alkynyl Ketones and Naphthols using the TCDC Approach

“…In further studies, we have demonstrated that naphthols can also be used as nucleophiles in the same tandem reactions [7d] …”

“…Our own studies [7d] established that, under CPAPhosAuCl catalysis, 2‐naphthols can behave as O ‐and/or C ‐nucleophiles [10] in their reaction with 1 , and that high enantioselectivities can be reached for both products 4 and 5 (Scheme 2, eq. 2), nicely complementing Ren's findings [9] .…”

“…On the basis of the catalytic tests in ref. [7d] and the control experiments above, we have pictured a plausible mechanism accounting for the outcomes of the catalytic reactions, including the erosion of the enantiomeric excess of compound 4 a and its conversion into 5 a (Scheme 5). These mechanistic issues are outlined hereafter.…”

Asymmetric gold catalysis enabled by specially designed ligands

“…Very recently, Frison, Marinetti and Guinchard reported the gold( i )-catalysed enantioselective cycloisomerization/nucleophilic addition reaction of 2-alkynylenones ( 13a ) with naphthols ( 13k ) to produce bicyclic furans ( 13l and 13m ) (Scheme 13D). 113 The gold complexes of both ligands ( L13A and L13B ) can facilitate the desired reactions at low catalytic loading (0.2 to 1 mol%) and with significant enantioselectivities. Naphthol acts as an O-centered and C-centered nucleophile, leading to the highly enantioenriched bicyclic furans 13l (up to 85% ee) and 13m (up to 99% ee) respectively.…”