Asymmetric Arylative Dearomatization of β‐Naphthols Catalyzed by a Chiral Phosphoric Acid

Abstract

An enantioselective arylative dearomatization reaction of β-naphthols with quinone monoimides has been developed for the first time using a chiral phosphoric acid as the catalyst, the desired enantioenriched cyclohexadienones were prepared with excellent yields and enantioselectivities by a domino Michael addition and aromatization process (up to 99 % yield, up to 98 % ee). This process is operationally simple and readily scaled up, as well as a broad substrate scope which includes 1-substituted-2-naphthols with/without 3-substituents. Furthermore, this organocatalytic procedure allows the lowering of catalyst loading to 0.5 mol % without considerable loss in reactivity and enantioselectivity.

Redox-Neutral Atom-Economic Pd(0)-Catalyzed Dearomatization of β-Naphthols with Alkynes toward Naphthalenones

“…The dearomatization of naphthols has received great attention because this transformation represented an ideal method for the rapid construction of densely functionalized naphthalenones, which are important components of natural products and therapeutic reagents (Figure ). Well-designed strategies such as alkylation, arylation, alkenylation, amination, and halogenation of naphthols as well as hypervalent iodine or transition-metal-catalyzed oxidation have been elegantly unveiled to target these frameworks. Recently, transition-metal-catalyzed allylic substitution reactions have emerged as an alternative method to realize dearomatization of naphthols with allyl carbonates or alcohols as the allylic reagents (Scheme a) .…”

Recent Advances in the Catalytic Dearomatization of Naphthols

“…A very similar approach was then reported by Zhou in 2017 that adapted the afore‐described protocol to quinone monoimides 58 as electrophiles. In this case, the BINOL‐based phosphoric acid Cat5 was elected as the best organocatalyst, affording the cyclohexadienones 59 in very high chemical and optical yield (Scheme b) …”

Asymmetric Dearomative (3+2)-Cycloaddition Involving Nitro-Substituted Benzoheteroarenes under H-Bonding Catalysis

“…CADA reactions are primarily focused on transformations involving structurally simple electron-rich arenes and heteroarenes, such as naphthols [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ], phenols [ 19 , 20 ], indoles [ 21 , 22 , 23 , 24 ], and pyrroles [ 25 , 26 , 27 , 28 ]. The application of (hetero)aromatic reactants as electrophilic counterparts in such strategies is much less common.…”