51595-06-3

Upstream product

• 2876-35-9 2-tert-butylnaphthalene 
• 27286-81-3 2-(tert-butyl)-1-naphthol 
• 546-67-8 lead(IV) tetraacetate 
• 35448-10-3 oxalic acid mono-tert-butyl ester 
• 130-15-4 [1,4]naphthoquinone 
• 38442-51-2 tert-butylmercury chloride 
• 89025-50-3 2,2-dimethylpropionic acid 2-thioxo-2H-pyridin-1-yl ester 
• 75-98-9 Trimethylacetic acid 
• 571-60-8 1,4-Dihydroxynaphthalene 
• 75-65-0 tert-butyl alcohol 
• 90-15-3 α-naphthol 
• 917-92-0 3,3-Dimethylbut-1-yne 
• 4900-63-4 1-methoxy-4-nitronaphthalene 
• 27436-93-7 pentacarbonyl(1-methoxybenzylidene)chromium⁽⁰⁾ 

Relevant academic research and scientific papers

Stereoselective [4+2] cycloaddition of singlet oxygen to naphthalenes controlled by carbohydrates

Stereoselective reactions of singlet oxygen are of current interest. Since enantioselective photooxygenations have not been realized efficiently, auxiliary control is an attractive alternative. However, the obtained peroxides are often too labile for isolation or further transformations into enantiomerically pure products. Herein, we describe the oxidation of naphthalenes by singlet oxygen, where the face selectivity is controlled by carbohydrates for the first time. The synthesis of the precursors is easily achieved starting from naphthoquinone and a protected glucose derivative in only two steps. Photooxygenations proceed smoothly at low temperature, and we detected the corresponding endoperoxides as sole products by NMR. They are labile and can thermally react back to the parent naphthalenes and singlet oxygen. However, we could isolate and characterize two enantiomerically pure peroxides, which are sufficiently stable at room temperature. An interesting influence of substituents on the stereoselectivities of the photooxygenations has been found, ranging from 51:49 to up to 91:9 dr (diastereomeric ratio). We explain this by a hindered rotation of the carbohydrate substituents, substantiated by a combination of NOESY measurements and theoretical calculations. Finally, we could transfer the chiral information from a pure endoperoxide to an epoxide, which was isolated after cleavage of the sugar chiral auxiliary in enantiomerically pure form.

Formation of naphthoquinones and anthraquinones by carbonyl-hydroquinone/benzoquinone reactions: A potential route for the origin of 9,10-anthraquinone in tea

The reaction of 2-alkenals (crotonaldehyde and 2-pentenal) with hydroquinones (hydroquinone and tert-butylhydroquinone) and benzoquinones (benzoquinone, methylbenzoquinone, and methoxybenzoquinone) was studied as a potential route for the endogenous formation of naphthoquinones and anthraquinones in foods. Polycyclic quinones were produced at a low water activity, within a wide pH range, and in the presence of air. 9,10-Anthraquinone formation had an activation energy of 46.1 ± 0.1 kJ·mol?1, and a reaction pathway for the formation of the different naphthoquinones and anthraquinones is proposed. These reactions also took place in tea, therefore suggesting that the common tea pollutant 9,10-anthraquinone is also a process-induced contaminant. In fact, when four commercial teas (from a total of eight studied teas) were heated at 60 °C for 72 h, they significantly (p 0.05) increased the amount of this toxicant. Reduction of 9,10-anthraquinone formation in teas is suggested to be carried out by reducing/scavenging its precursors.

Activated Carbon-Promoted Dehydrogenation of Hydroquinones to Benzoquinones, Naphthoquinones, and Anthraquinones under Molecular Oxygen Atmosphere

We found that the activated carbon-molecular oxygen system promotes the conversion of hydroquinones to benzoquinones, naphthoquinones, and anthraquinones, which are often found in natural products and pharmaceuticals. In particular, the one-pot synthesis of naphthoquinones and anthraquinones involving a Diels-Alder reaction is a useful protocol for this purpose.

CuI/Cu(OTf)2/DMSO system-catalyzed intramolecular oxidative cyclization of (o-alkynyl)arylketones: Efficient synthesis of 1,4-naphthoquinones

A concise and efficient method for the synthesis of 1,4-naphthoquinones has been successfully developed involving a CuI/Cu(OTf)2/DMSO system-catalyzed intramolecular oxidative cyclization of (o-alkynyl)arylketones. The present protocol provided a novel approach to access functionalized 1,4-naphthoquinones from non-naphthoquinone precursors with good selectivity and functional group tolerance.

Metal-, Photocatalyst-, and Light-Free, Late-Stage C-H Alkylation of Heteroarenes and 1,4-Quinones Using Carboxylic Acids

Contrary to the accepted convention, this work shows that Minisci-type C-H alkylation does not require any metal, photocatalyst, light, or prefunctionalization of the readily available and inexpensive carboxylic acids to proceed well under mild conditions. These mild conditions can be utilized for late-stage alkylations of complex molecules, including pharmaceutical compounds and light-sensitive compounds which degrade under photocatalytic conditions.

Radical-Triggered Tandem Cyclization of 1,6-Enynes with H2O: A Way to Access Strained 1 H-Cyclopropa[ b]naph thalene-2,7-diones

A radical-triggered tandem cyclization of 1,6-enynes has been developed herein. Strained 1H-cyclopropa[b]naphthalene-2,7-diones are successfully obtained in moderate to good yields with excellent stereoselectivity. Mechanistic studies reveal a key role of water in generating a hydroxyl radical that initiates a sequential Michael addition/ring closure pathway. Importantly, the formed hydroxyl is proposed to be a good leaving group during the cyclopropane ring formation.

Synthetic method for 2-substituted-1,4-naphthoquinone derivatives

The invention discloses a synthetic method for 2-substituted-1,4-naphthoquinone derivatives. The method comprises the following steps: with 2-alkynylacetophenone compounds as shown in a formula I which is described in the specification as a raw material and dimethyl sulfoxide as an oxidizing agent and a solvent, carrying out a reaction at 80 to 140 DEG C under stirring and the action of a copper catalyst for 2 to 10 h; and subjecting a reaction solution obtained after completion of the reaction to post-treatment so as to obtain the 2-substituted-1,4-naphthoquinone derivatives as shown in a formula II which is described in the specification, wherein the copper catalyst is a mixture of bis(copper trifluoromethanesulfonate) and an inorganic cuprous salt, and the inorganic cuprous salt is one selected from a group consisting of cuprous iodide, cuprous chloride, cuprous bromide and cuprous cyanide. The method has the advantages that the raw materials are variable; the number of the prepared derivatives is great; the catalyst is cheap and easily available; cost is substantially reduced; no pollution is produced; no extra oxidizing agent is needed; dimethyl sulfoxide both functions as the oxygen source and the solvent, so cost is saved; and the method has the characteristics of high reaction yield, good substrate applicability, simple operation, etc.

Alkyne competition in the benzannulation reaction with chromium carbene complexes

(Figure presented) The benzannulation reaction of Fischer carbene complexes is investigated under conditions where the reaction of the carbene complex is occurring in the presence of two different alkynes. A series of competition experiments are examined where the effects of various structural factors are explored by pitting 10 different carbene complexes with 11 different alkynes. Terminal alkynes will react selectively over internal alkynes in all cases examined including both aryl and alkenyl complexes. Aryl carbene complexes with methoxy substituents do not give quite as high selectivity for terminal alkynes over internal alkynes (～95:5) as do isopropoxy substituents (>99:1), whereas most alkenyl complexes give high selectivity with both substituents (>99:1). Competition experiments between two different terminal alkynes or between two different internal alkynes did not result in anything more than very modest selectivities at best (～2:1). Excellent selectivities were realized between two different terminal acetylenes if one of the terminal acetylene was protected with a trimethylsilyl group. Finally, it was demonstrated that the high selectivities between terminal and internal alkynes can be utilized in the reaction with molecules that contain both types of alkyne functions.

Enantioselective epoxidation of 2-substituted 1,4-naphthoquinones using gem-dihydroperoxides

New gem-dihydroperoxides were successfully used for DBU-promoted enantioselective epoxidation of 2-substituted 1,4-naphthoquinones. The corresponding 1,4-naphthoquinone epoxides were obtained in yields up to 97% and ee's up to 82%.

Study of radical decarboxylation toward functionalization of naphthoquinones

In order to obtain functionalized naphthoquinones, a systematic study of the Kochi-Anderson procedure for the alkylation of quinones is presented. While linear amino acids of different lengths were good substrates for this decarboxylation procedure, chira