542-08-5Relevant articles and documents
Enantioselective aldol-type reaction using diketene
Kawase, Takahiro,Takizawa, Shinobu,Jayaprakash, Doss,Sasai, Hiroaki
, p. 4487 - 4492 (2004)
An aldol-type reaction catalyzed by a Ti-(S)-BINOL complex using with a diketene as substrate is described herein. The complex derived from 1.0 molar equivalent of Ti(O-i-Pr)4 and 2.0 molar equivalents of (S)-BINOL gave (5)-isopropyl 5-hydroxy-7-phenyl-3-oxo-6-heptenoate with high enantioselectivity.
Br?nsted acidic cellulose-PO3H: An efficient catalyst for the chemoselective synthesis of fructones and trans-esterification via condensation of acetoacetic esters with alcohols and diols
Naikwadi, Dhanaji R.,Singh, Amravati S.,Biradar, Ankush V.
, (2021/10/04)
Cellulose is the most abundant organic source and has expedient a great deal of interest as renewable and emerged as sustainable feedstock. The functionalization of cellulose as designed catalytic system intriguing furnished to the production of fine chemicals. Herein, we synthesized an environmental friendly solid acid catalyst by functionalizing cellulose with phosphoric acid (PO3H). The successful functionalization of cellulose with PO3H was confirmed by 31P NMR, ICP-OES, FE-SEM, and XPS analysis. ICP-OES revealed the presence of phosphorus content of ~1.0 wt. % on the catalyst's surface while elemental mapping by FESEM and XPS shows a uniform distribution of phosphorus over the material. The synthesized solid acid catalyst was utilized for condensation of diols with acetoacetic esters in solvent-free conditions to synthesize fine chemicals. The present approach not only circumvented the one-step protection and other products but more fascinatingly provided trans-esterification of acetoacetic esters with diols and n-alcohols. The catalyst was successfully used for chemoselective protection on ethyl acetoacetate with 1, 2 diols to essential fructone molecule with ~100% conversion and 99% selectivity. The results suggested that the catalyst has the advantage over commercial solid acid heterogeneous and homogeneous catalysts.
Nimodipine impurity IV reference substance as well as preparation method and application thereof
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Paragraph 0051-0052, (2020/11/22)
The invention discloses a nimodipine impurity IV reference substance and a preparation method thereof. The method includes the steps that diketene, ethyl alcohol and triethylamine are taken and addedinto a container to be heated and cooled, reaction liquid is washed with water, washing liquid is discarded, anhydrous sodium sulfate is added and placed overnight, filtrate is obtained after filtration, ammonia gas is introduced into the filtrate until the filtrate is saturated, and the nimodipine impurity IV reference substance is obtained; and after the reaction is finished, m-nitrobenzaldehyde, methoxyethyl acetoacetate and ethanol are added, heating refulx is performed, the mixture is cooled and filtered, the solvent is removed through volatilization in a water bath to obtain a yellow viscous liquid, and recrystallization is carried out to obtain a yellow acicular crystal, namely the nimodipine impurity IV reference substance. The invention also discloses an application of the nimodipine impurity IV reference substance in nimodipine tablet consistency evaluation. According to the preparation method, the impurity IV can be prepared in a general analysis laboratory, special preparation equipment is not needed, the operation is simple, the purity of the obtained impurity reference substance can reach 98.4%, the purity requirement of the reference substance is met, and the preparation method can be used for consistency evaluation of the variety.