92-44-4Relevant articles and documents
Identification of molecular crystals capable of undergoing an acyl-transfer reaction based on intermolecular interactions in the crystal lattice
Tamboli, Majid I.,Krishnaswamy, Shobhana,Gonnade, Rajesh G.,Shashidhar, Mysore S.
, p. 12867 - 12874 (2013)
Investigation of the intermolecular acyl-transfer reactivity in molecular crystals of myo-inositol orthoester derivatives and its correlation with crystal structures enabled us to identify the essential parameters to support efficient acyl-transfer reactions in crystals: 1)a the favorable geometry of the nucleophile (-OH) and the electrophile (C-O) and 2)a the molecular assembly, reinforced by C-H×××π interactions, which supports a domino-type reaction in crystals. These parameters were used to identify another reactive crystal through a data-mining study of the Cambridge Structural Database. A 2:1 co-crystal of 2,3-naphthalene diol and its di-p-methylbenzoate was selected as a potentially reactive crystal and its reactivity was tested by heating the co-crystals in the presence of solid sodium carbonate. A facile intermolecular p-toluoyl group transfer was observed as predicted. The successful identification of reactive crystals opens up a new method for the detection of molecular crystals capable of exhibiting acyl-transfer reactivity. Reactive crystal gazing? Characterization of functional groups in small organic molecules allows the prediction of their reactivity in solution, and often the structure of the resulting products with fairly good accuracy. This, however, is not true for reactions in the solid state. It was demonstrated that an understanding of the non-covalent interactions in molecular crystals can aid in identifying crystal structures that support chemical reactions (see figure). Copyright
Terbium(iii)-cholate functionalized vesicles as luminescent indicators for the enzymatic conversion of dihydroxynaphthalene diesters
Balk, Stefan,Maitra, Uday,Koenig, Burkhard
, p. 7852 - 7854 (2014)
The phosphorescence intensity of unilamellar DOPC vesicles with embedded Tb3+-cholate complexes depends on the concentration of dihydroxynaphthalene (DHN) as sensitizer in solution. This was used to monitor the enzymatic conversion of DHN esters or DHN glucosides by enzymes in aqueous buffered solution. This journal is the Partner Organisations 2014.
Construction of Two-Component Chemically Reactive Supramolecular Assemblies-Acyl Migration Reactions in Cocrystals of Napthalene-2,3-Diol and Its Diesters
Bahadur, Vir,Gonnade, Rajesh G.,Krishnaswamy, Shobhana,Shashidhar, Mysore S.,Tamboli, Majid I.
, p. 1128 - 1134 (2021)
Reactions in solids are of contemporary interest due to applications in pharmaceutical industries to environmental sustainability. Although several reactive crystals that support chemical reactions have been identified and characterized, the same cannot be said about reactive cocrystals. Earlier we correlated the facile acyl group transfer reactions in crystals with supramolecular parameters obtained from the crystal structures. The structure-reactivity correlation revealed the requirement of proper juxtaposition of electrophile (C=O) and the nucleophile (OH) with distance (～3.2 ?) and angle (～90°) along the chain structure. The current article describes the preparation of cocrystals that are capable of supporting intermolecular acyl group transfer reactions in a group of structurally similar molecules. The cocrystals of naphthalene 2,3-diol and its corresponding diesters showed a facile solid state acyl transfer reaction, which has been well correlated with their crystal structures.
Oxygen-Free Regioselective Biocatalytic Demethylation of Methyl-phenyl Ethers via Methyltransfer Employing Veratrol- O-demethylase
Grimm, Christopher,Lazzarotto, Mattia,Pompei, Simona,Schichler, Johanna,Richter, Nina,Farnberger, Judith E.,Fuchs, Michael,Kroutil, Wolfgang
, p. 10375 - 10380 (2020/10/02)
The cleavage of aryl methyl ethers is a common reaction in chemistry requiring rather harsh conditions; consequently, it is prone to undesired reactions and lacks regioselectivity. Nevertheless, O-demethylation of aryl methyl ethers is a tool to valorize natural and pharmaceutical compounds by deprotecting reactive hydroxyl moieties. Various oxidative enzymes are known to catalyze this reaction at the expense of molecular oxygen, which may lead in the case of phenols/catechols to undesired side reactions (e.g., oxidation, polymerization). Here an oxygen-independent demethylation via methyl transfer is presented employing a cobalamin-dependent veratrol-O-demethylase (vdmB). The biocatalytic demethylation transforms a variety of aryl methyl ethers with two functional methoxy moieties either in 1,2-position or in 1,3-position. Biocatalytic reactions enabled, for instance, the regioselective monodemethylation of substituted 3,4-dimethoxy phenol as well as the monodemethylation of 1,3,5-trimethoxybenzene. The methyltransferase vdmB was also successfully applied for the regioselective demethylation of natural compounds such as papaverine and rac-yatein. The approach presented here represents an alternative to chemical and enzymatic demethylation concepts and allows performing regioselective demethylation in the absence of oxygen under mild conditions, representing a valuable extension of the synthetic repertoire to modify pharmaceuticals and diversify natural products.
Selective Vicinal Diiodination of Polycyclic Aromatic Hydrocarbons
Bolte, Michael,Jin, Tao,John, Alexandra,Kaehler, Tanja,Lerner, Hans-Wolfram,Wagner, Matthias
supporting information, p. 5847 - 5851 (2020/09/09)
Vicinally diiodinated polycyclic aromatic hydrocarbons (I2-PAHs) are accessible from the corresponding diborylated B2-PAHs through boron/iodine exchange. The B2-PAHs have been prepared via twofold electrophilic borylation reactions templated by a vicinally disilylated benzene. Our protocol is applicable to fluorenes, acenes, annulated acenes, oligoaryls, and even [5]helicene. Using B2-naphthalene as the example, we have shown that the reaction scope can, in principle, be expanded to include the synthesis of vicinally dibrominated and dihydroxylated PAHs. The usefulness of the building blocks provided by our method in the field of optoelectronic materials was demonstrated by the successful conversion of I2-fluoranthene to the analogous doubly alkynylated fluoranthene emitter.
Practical Cleavage of Acetals by Using an Odorless Thiol Immobilized on Silica
de Léséleuc, Mylène,Kukor, Andrew,Abbott, Shaun D.,Zacharie, Boulos
, p. 7389 - 7393 (2019/12/03)
A practical, efficient and general method was developed for the deprotection of a variety of aromatic and aliphatic acetals to their corresponding catechol or diol derivatives using thiol immobilized on silica gel. This is an application for the well-known commercial solid-supported thiol (SiliaMetS Thiol). The procedure is mild and amenable to scale-up. It does not require inert atmosphere and clean conversions were observed. This method is applicable to substituted 1,3-benzodioxole and aliphatic acetals with different functionalities. It offers the advantage of a general route with high yield, which can be undertaken at ambient temperature.
Method for synthesizing 2,3-dioxynaphthalene
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Paragraph 0021; 0023; 0025; 0027; 0029; 0031; 0033; 0035, (2018/09/11)
The invention relates to a method for synthesizing 2,3-dioxynaphthalene. The method comprises the following steps: adding naphthalene, a catalyst and an auxiliary in a reaction solvent; heating to thetemperature of 30-70 DEG C while stirring; then dropwise adding hydrogen peroxide with the concentration being 30%; and reacting to obtain a 2,3-dioxynaphthalene solution. Compared with an existing process for preparing 2,3-dioxynaphthalene, the method for synthesizing 2,3-dioxynaphthalene is relatively low in cost and is environmentally friendly; a large number of acids and alkalis are requiredfor a traditional sulfonation and alkali fusion process and a large amount of acid-containing waste water caused by consumption of the large number of acids and alkalis are avoided, reaction conditions are gentle, energy consumption is low, and environmental protection is facilitated.
A rapid, solvent-free deprotection of methoxymethyl (MOM) ethers by pTSA; An eco-friendly approach
Pandurangan, Nanjan
, p. 231 - 235 (2017/07/15)
Background: Ease of preparation and alkaline stability of methoxymethyl (MOM) makes it an important hydroxyl protecting group. A number of methods are available for the deprotection of MOM. Though the methods are good in general, they use solvents, require prolonged reaction time and tedious work up. A solvent free, solid phase, fast deprotection of MOM has been developed and is the major theme of this paper. Methods: A mixture of MOM protected compounds and pTSA is triturated in a mortar (5 min) and left at room temperature for 30 min. On addition of water (4°C), pTSA, methanol and formaldehyde dissolved leaving the products as precipitates. Results: A series of different MOM ethers were deprotected by this method in good to excellent yield (85-98%). The compatibility of MOM in the presence of other protections such as methoxyl, benzyl, ester, amide, allyl and lactone was also established. Acetate protection is not stable under these conditions. Conclusion: An efficient, selective and high yielding deprotection MOM groups by pTSA under solvent free condition is described. The process is environment friendly since no solvent was used in the deprotection process. The reaction conditions are mild and should be useful for the deprotection of MOM derivatives of complex and labile molecules.
An efficient strategy for protecting dihydroxyl groups of catechols
Huang, Wei-Bin,Guo, Ying,Jiang, Jian-An,Pan, Xian-Dao,Liao, Dao-Hua,Ji, Ya-Fei
supporting information, p. 741 - 746 (2013/05/09)
A novel strategy for protecting dihydroxyl groups of catechols has been developed. Base-mediated cyclizations of catechols with 1,3-dibromopropane provided the corresponding benzo[b]1,4-dioxepans, and herefrom the protecting group was easily cleaved by aluminum chloride. The preparation of the antibacterial and antifungal agent 4-(2-aminothiazol-4-yl)benzene-1,2-diol from catechol reliably verified its availability amenable to various harsh reaction conditions. Georg Thieme Verlag Stuttgart - New York.
Synthesis and use of ortho-(branched alkoxy)-tert-butoxybenzenes
Rast, Slavko,Stephan, Michel,Mohar, Barbara
supporting information, p. 6815 - 6818 (2013/01/15)
A series of sterically hindered o-(branched alkoxy)-tert-butoxybenzenes was efficiently prepared in good yields owing to a new practical and simple preparation of o-tert-butoxyphenol starting from catechol and isobutene. Use of DMF di-tert-butyl acetal reagent instead of isobutene/H2SO 4 (cat.) for O-tert-butylation was very convenient in case of ortho bulky phenols affording the corresponding tert-butyl ethers in high yield and purity. This general route proved to be useful since no reliable access was available to o-di-t-BuO-substituted arenes. Application to the synthesis of congested phosphorus-based compounds is presented.
