Asymmetric Dearomatization of β‐Naphthols through an Amination Reaction Catalyzed by a Chiral Phosphoric Acid

A highly efficient catalytic asymmetric dearomatization of naphthols by means of an electrophilic amination reaction catalyzed by chiral phosphoric acid is presented. This protocol provides a facile access to functionalized β‐naphthalenone compounds with a chiral quaternary carbon center in excellent yields and enantioselectivity (up to 99 % yield, up to 96 % ee).     

Palladium(0)‐Catalyzed Intermolecular Arylative Dearomatization of β‐Naphthols

The first Pd⁰‐catalyzed intermolecular arylative dearomatization of β‐naphthols with aryl halides is described. It was found that Q‐Phos could facilitate the palladium‐catalyzed cross‐coupling‐type dearomatization of β‐naphthols, while avoiding O‐arylation, to construct 2‐naphthalenones in excellent yields and with high chemoselectivity.     

BAIB Oxidation to Some Tetrahydro‐β‐naphthols and Control over the Products by Reaction Condition Selection

Using two different conditions for the BAIB [bis(acetoxyiodo)benzene] oxidation to tetrahydro‐β‐naphthols or substituted tetrahydro‐β‐naphthols furnished two different products with excellent yields.     

通过不对称氢转移/动态动力学拆分合成碳环N^3-嘌呤核苷

N^3-嘌呤核苷由于可能同时被嘌呤和嘧啶代谢酶识别,因而有望作为双靶点药物应用于抗病毒治疗.报道了一种以α-(N^3-嘌呤)取代的环烷酮为原料,通过不对称氢转移反应实现动态动力学拆分,高收率高立体选择性地合成系列碳环N^3-嘌呤核苷化合物.该催化体系也适用于α-嘧啶取代的环烷酮底物,且产物通过进一步衍生,合成了2’-F-,Ac S-,N^3-修饰的碳环嘧啶核苷.     

A One-Pot Approach for Bio-Based Arylamines via a Combined Photooxidative Dearomatization-Rearomatization Strategy

The synthesis of arylamines from renewable resources under mild reaction conditions is highly desired for the sustainability of the chemical industry, where the production of hazardous waste is a prime concern. However, to date, there are very few tools in chemists’ toolboxes that are able to produce arylamines in a sustainable manner. Herein, a robust one-pot approach for constructing bio-based arylamines via a combined photooxidative dearomatization-rearomatization strategy is presented. The developed methodology enables the synthesis of structurally complex amines in moderate-to-good isolated yields using biomass-derived phenols, natural α-amino acids, and naphthols under remarkably mild reaction conditions. For the photooxygenation of phenols, a novel chrysazine-based catalyst system was introduced, demonstrating its efficiency for the synthesis of natural products – hallerone, rengyolone, and the pharmaceutically relevant prodrug DHED.     

Phosphomolybdic acid as a bifunctional catalyst for Friedel–Crafts type dehydrative coupling reaction

Phosphomolybdic acid (H₃PMo₁₂O₄₀) was found to be a bifunctional catalyst for C─C bond formation via the dehydrative reaction of diarylmethanols with various nucleophiles, including 2‐naphthols, indoles, benzofuran and benzothiophene. The protons in the catalyst might play a critical role in the activation of alcohol, while the polyanion was advantageous for stabilizing the carbocation species. The cooperative catalytic system showed its own merits, such as high reaction rate, low catalyst loading, mild conditions, excellent yields (up to 99%) and good functional group compatibility.     

Organocatalytic Asymmetric Addition of Naphthols and Electron‐Rich Phenols to Isatin‐Derived Ketimines: Highly Enantioselective Construction of Tetrasubstituted Stereocenters

A quinine‐derived thiourea organocatalyst promoted the highly enantioselective addition of naphthols and activated phenols to ketimines derived from isatins. The reaction afforded chiral 3‐amino‐2‐oxindoles with a quaternary stereocenter in high yields (up to 99 %) with excellent enantioselectivity (up to 99 % ee). To the best of our knowledge, this transformation is the first highly enantioselective addition of naphthols to ketimines.     

Efficient microwave-assisted direct C-benzoylation of phenols and naphthols with benzoic acid catalyzed by bismuth triflate under solvent-free or ionic liquid conditions

An efficient and simple route for the synthesis of ortho-hydroxyaryl ketones has been developed. The microwave-assisted direct C-benzoylation of phenols and naphthols in the presence of metal triflates afforded the corresponding ortho-hydroxyaryl ketones in moderate to excellent yields. Bismuth triflate showed the best catalytic performance compared to other metal triflates. The protocol has advantages including short reaction times, high chemoselectivity towards C-acylation, and simple work-up. Additionally, bismuth triflate can be easily recovered and reused several times without significant loss of catalytic performance.     

Environmentally Friendly Preparation of Amidoalkyl Naphthols

A new, facile, and cost-effective process involving the solvent-free synthesis of amidoalkyl naphthols using a three-component, one-pot condensation reaction of β-naphthol, aromatic aldehyde, and amides in the presence of Al(H₂PO₄)₃ as heterogeneous catalyst under thermal conditions and microwave irradiation has been described. This new approach has the advantage of consistently excellent yields and short reaction times. The catalyst has shown a very stable catalytic activity in the reaction conditions and also can be recovered and recycled.     

Three component,one-pot synthesis of amidoalkyl naphthols using polyphosphate ester under solvent-free conditions

Amidoalkyl naphthols are synthesized via a simple, one-pot, three-component reaction between aldehydes, 2-naphthol and amides or ureas using polyphosphate ester (PPE) as a reaction mediator under solvent-free conditions in good to excellent yields. High yields, short reaction time, easy work-up, elimination of solvents and toxic catalysts are the advantages of this procedure.     

Iodine assisted palladium catalyzed ring opening of bicyclic hydrazines with organoboronic acids: stereoselective synthesis of functionalized cyclopentenes and alkylidene cyclopentenes

A novel reactivity of organoboronic acids with bicyclic hydrazines leading to the stereoselective formation of trans-vicinal disubstituted cyclopentenes in good to excellent yield is discussed. The reaction of cyclopentadiene and fulvene derived azabicyclic alkenes with organoboronic acids afforded the trans-3,4-disubstituted cyclopentenes and alkylidene cyclopentenes in good to excellent yields. The products, having a broad range of substituents, are important intermediates in the synthesis of a number of pharmaceutically important molecules.     

Catalytic Enantioselective Addition of Thioacids to Trisubstituted Nitroalkenes

The first example of a catalytic enantioselective addition to and nitronate protonation of trisubstituted nitroalkenes to produce highly enantioenriched products with a tetrasubstituted carbon is reported. Thioacids added in excellent yields and with high enantioselectivities to both activated and unactivated nitroalkenes. The 1,2‐nitrothioacetate products can be readily converted in two steps to biomedically relevant 1,2‐aminosulfonic acids without loss of enantiopurity.     

Solvent‐Free One‐Pot Synthesis of Amidoalkyl Naphthols Catalyzed by Silica Sulfuric Acid

An efficient, inexpensive, and mild method for the synthesis of amidoalkyl naphthols, catalyzed by ‘silica sulfuric acid’ (SSA), was elaborated under solvent‐free conditions at room temperature. Various amidoalkyl naphthols were synthesized in high yields from aromatic or aliphatic aldehydes, α‐ or β‐naphthols, and amides or urea or thiourea.     

Brønsted acid-catalyzed imine amidation

A new method for the Br?nsted acid-catalyzed addition of amide nucleophiles to imines to produce protected aminal products is described. Simple Br?nsted acids (phenyl phosphinic acid and trifluoromethanesulfonimide) were shown to be excellent catalysts, providing high yields of the aminal product. A catalytic asymmetric imine amidation using sulfonamides as nucleophiles was successful when a hindered biaryl phosphoric acid catalyst derived from 2,2'-diphenyl-[3,3'-biphenanthrene]-4,4'-diol (VAPOL) was used. Excellent yields and enantioselectivities were found in these additions (up to 99% ee).     

Synthesis of 3-substituted trans-2-oxadecalins and 1-substituted trans-2-oxahydrindanes

A study was carried out of the intramolecular cyclization of trans-1-methoxymethyl-2-(1-hydroxyalkyl)cyclohexanes and trans-1-methoxymethyl-2-(2-hydroxyalkyl)cyclohexanes by the action of acid chlorides of phosphorous, sulfurous and p-toluenesulfonic acids with the formation of 1-substituted trans-2-oxahydrindanes in low yields and 3-substituted trans-2-oxadecalins in high yields. A relationship has been established between the yields of the cyclization products and the nature of the halogenating agent. The cyclization does not proceed via an intermediate oxonium ion, but by means of an intermolecular electronic transition.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1865–1877, August, 1991.     

Solvent-free,highly efficient one-pot multi-component synthesis of 1-amido- and 1-carbamato-alkyl naphthols/phenols catalyzed by ethylammonium nitrate as reusable ionic liquid under neat reaction condition at ambient temperature

A solvent-free, environmentally clean, mild, and simple one-pot multi-component protocol has been developed for the efficient synthesis of 1-amido- and 1-carbamato-alkyl naphthols/phenols in excellent yields via one-pot three-component condensation of various aldehydes, amides/carbamates/urea, and naphthols/phenols using ethylammonium nitrate (EAN) as a reusable ionic liquid catalyst under neat reaction condition at ambient temperature.     

Three-component synthesis of amidoalkyl naphthols catalyzed by bismuth(III) nitrate pentahydrate

Bismuth(Ⅲ) nitrate pentahydrate catalyzed the three-component condensation ofβ-naphthol,aldehydes and amines/urea under solvent-free conditions to afford the corresponding amidoalkyl naphthols in excellent yields.     

Copper‐Catalyzed Oxidative Dearomatization of 2‐Naphthols via Etherification

Copper‐catalyzed intermolecular oxidative‐etherification type dearomatization reaction of 2‐naphthols was developed. With air as the terminal oxidant, the reaction proceeded in excellent yields under mild conditions. In addition, the reaction between two different naphthol substrates occurred smoothly. A series of multifunctionalized β‐naphthalenones, important scaffold existed widely in natural products and biologically active molecules, were synthesized efficiently.     

Organocatalytic asymmetric chlorinative dearomatization of naphthols

An organocatalytic asymmetric chlorinative dearomatization of naphthols was realized for the first time, providing chiral naphthalenones with a Cl-containing all-substituted stereocenter in excellent yields and enantioselectivity (up to 97% yield and 96% ee). The reaction features mild reaction conditions, good tolerance of diverse functional groups and simple reaction operation.     

Facile synthesis of 2-substituted 1,2-dihydro-1-naphthols and 2-substituted 1-naphthols

[reaction: see text] The palladium-catalyzed ring opening of dimethoxy oxabenzonorbornadiene with aryl or vinyl halides occurred under very mild conditions to give substituted 1,2-dihydronaphthols that were oxidized with IBX to furnish substituted naphthols in excellent overall yields.