- Metal-Free Oxidative Condensation of Catechols, Aldehydes and NH4OAc towards Benzoxazoles
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Benzoxazoles extensively exist in biologically active compounds, natural products, pharmaceuticals and functional materials. Thus, facile and green synthesis of such valuable compounds from easily available substrates will make a contribution to drug, material, and fine chemistry. A method for the synthesis of benzoxazoles from catechols, aldehydes and ammonium acetate is developed using NaIO4 as oxidant under metal- and additive-free conditions. A broad range of benzoxazoles including some fluorescent whitening agents, JTP-426467 and tafamidis analogues are synthesized in 56–95% yields with outstanding functional group tolerance. Mechanistic investigations suggest that an interesting o-iminocyclohexa-diene alcohol intermediate is involved in the reaction. These salient features of the protocol make it an alternative for the synthesis of benzoxazoles. (Figure presented.).
- Dong, Jianyu,Geng, Furong,Su, Lebin,Wu, Shaofeng,Yin, Shuang-Feng,Zhou, Dan,Zhou, Yongbo
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supporting information
p. 3607 - 3614
(2021/07/28)
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- Production process of fluorescent whitening agent OB
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The present invention relates to a production process of a fluorescent whitening agent OB. The production process specifically comprises the following steps: adding trichlorobenzene to a material feeding kettle, starting stirring, sequentially adding OB phenol, OB acid and a catalyst boric acid, pumping toluene into the material feeding kettle, uniformly stirring, pumping into a condensation kettle through a material pouring pump, introducing 99.9% nitrogen gas into the condensation kettle, and preventing the material from being oxidized, heating the material to 160-180 DEG C, starting a condensation dehydration reaction, continuing heating reaction dehydration until the temperature of the material is increased to 230-250 DEG C, evaporating methylbenzene in the dehydration process, and ending the reaction when no water is removed from the reaction material; then starting system negative pressure to evaporate trichlorobenzene out of the condensation kettle until trichlorobenzene is completely evaporated out so as to obtain a molten crude product material; the process is simple in process, high in yield and high in product purity.
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Paragraph 0022-0050
(2021/03/13)
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- Process for preparing particles which have a hydrophilic core coated with a hydrophobic polymeric layer
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This method of preparing particles having a hydrophilic core coated with a hydrophilic core coated with a hydrophobic polymeric layer includes the steps of: preparing an aqueous phase comprising at least one hydrophilic optical brightener or colorant; preparing an organic phase including at least one hydrophobic polymer; forming a water-in-oil inverse emulsion by adding the aqueous phase into the organic phase; forming the particles by thermal quenching of the emulsion; and isolating the particles thus obtained.
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- Process for the preparation of bis-benzazolyl compounds
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The present invention provides a process for the preparation of a compound of formula (I) wherein Y represents —O—, —S— or —N(R2)—, R2 being hydrogen, C1-C10alkyl or aralkyl; Z represents a 2,5-furanyl, 2,5-thiophenyl, 4,4′-stilbenyl or a 1,2-ethyleny residue and R1 represents hydrogen, halogen, C1-C10alkoxyl, cyano, COOM or SO3M, M being hydrogen or an alkaline or alkaline earth metal, characterized by reacting a compound of formula (II) with a dicarboxylic acid of formula (III): HOOC-Z-COOH, or an ester thererof, Y, Z and R1 being as previously defined, in N-methylpyrrolidone or N,N-dimethylacetamide, in the presence of an acidic catalyst and, optionally, in the presence of a secondary solvent capable of removing water from the reaction mixture, which are useful as optical whitening agents for natural and synthetic materials.
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Page/Page column 3
(2008/06/13)
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- Eine einfache Methode zur Herstellung von Benzoxazolen
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The preparation of benzoxazoles by a facile one-pot reaction is reported.The reaction of carboxylic acids with 2-chloro-N-methyl-Δ1-pyrrolinium chloride in an excess of N-methyl-2-pyrrolidone afforded carboxylic acid chlorides which were converted subsequently to their 2-hydroxyanilides by addition of 2-aminophenols.Cyclization of the 2-hydroxy-anilides at elevated temperatures furnished the benzoxazoles in high yield and purity.
- Seha, Zdenek,Weis, Claus D
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p. 413 - 419
(2007/10/02)
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