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Method for preparing 2-amino benzothiazine

A technology of aminobenzene and thiazine, which is applied in the field of catalytic preparation of 2-aminobenzothiazine, can solve the problems of high price of noble metal catalysts, limitation of the application of existing technologies, and complicated raw materials used, so as to facilitate purification and simple post-treatment , easy-to-obtain effect

Inactive Publication Date: 2013-08-07
SUZHOU UNIV
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  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0006] Q. Ding used Ag(OTf) as a catalyst to synthesize 2-aminobenzothiazine from 2-alkynylaniline and isothiocyanate, with a yield of 50-96%; Tang used AgBF 4 As a catalyst, 2-aminobenzothiazine was prepared from 2-alkynylaniline and isothiocyanate through ammonolytic cyclization series reaction (see ①Q. Ding, et al. J. Comb. Chem. 2008, 10, 541; ②R. Y. Tang, et al. Synlett 2010, 1345); but the noble metal catalysts used are expensive
[0007] In addition, reaction conditions such as the use of refluxed organic solvents as the reaction medium, the complexity of the raw materials used, and the multi-step reaction process also limit the application of the prior art.

Method used

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  • Method for preparing 2-amino benzothiazine
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  • Method for preparing 2-amino benzothiazine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] Embodiment one: Catalyst Yb (OTf) 3 Synthesis

[0034] In the reaction flask, an excess of ytterbium oxide with a purity of 99.9% was added to an aqueous solution of trifluoromethanesulfonic acid (the volume ratio of acid to water was 1:1), and heated to reflux for 60 minutes; the unreacted ytterbium oxide was removed by filtration, and the Remove water under pressure to obtain ytterbium trifluoromethanesulfonate with crystal water; finally vacuum dehydrate at 180°C-200°C for 36-48 hours to obtain the desired ytterbium triflate Yb(OTf) 3 .

[0035] Other Ln(OTf) 3 Catalyst can refer to the preparation method of Example 1.

Embodiment

[0036] Example : La(OTf) 3 Synthesis of 2-Aminobenzothiazine by Catalytic Reaction of Ethyl o-Aminocinnamate and Phenyl Isothiocyanate

[0037] Weigh La(OTf) into a dry reaction flask 3 (0.0059 g, 0.01 mmol ), added ethyl o-aminocinnamate (0.1912 g, 1 mmol ) and phenylisothiocyanate (0.1622 g, 1.2 mmol ) in sequence, stirred at 50°C for 4 hours after mixing, added water Terminate the reaction, extract three times with ethyl acetate, dry the extract with anhydrous sodium sulfate, filter, remove the solvent under reduced pressure, and finally perform flash column chromatography on a silica gel column (eluent: ethyl acetate:petroleum ether=1:10) to obtain White solid product, 84% yield.

[0038] The theoretical molecular formula of the obtained product and the main NMR test data are as follows. It can be seen from the analysis that the actual synthesized product is consistent with the theoretical analysis.

[0039]

[0040] 1H NMR (400 MHz, CDCl 3 ) δ7.57 (d, J = 8.0 ...

Embodiment 3

[0041] Embodiment three: Nd(OTf) 3 Preparation of 2-aminobenzothiazine by catalyzing the reaction between ethyl o-aminocinnamate and phenylisothiocyanate

[0042] Weigh Nd(OTf) into a dry reaction flask 3 (0.0059 g, 0.01 mmol ), added ethyl o-aminocinnamate (0.1912 g, 1 mmol ) and phenylisothiocyanate (0.1622 g, 1.2 mmol ) in sequence, stirred at 50°C for 4 hours after mixing, added water Terminate the reaction, extract three times with ethyl acetate, dry the extract with anhydrous sodium sulfate, filter, remove the solvent under reduced pressure, and finally perform flash column chromatography on a silica gel column (eluent: ethyl acetate:petroleum ether=1:10) to obtain White solid product, 85% yield.

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Abstract

The invention discloses a method for preparing 2-amino benzothiazine. The method comprises the steps of preparing the 2-amino benzothiazine by addition reaction of catalytic o-amino ethyl cinnamate and isothiocyanate under the catalysis of trifluoromethanesulfonic acid rare-earth compound Ln(OTf)3 serving as a catalyst, wherein Ln represents a triad rate-earth metal ion and is one of lanthanum, neodymium, samarium or ytterbium, OTf represents trifluoromethanesulfonic acid radical and the chemical structural formula of o-amino ethyl cinnamate is shown in the specification; and the general formula of the chemical structure of isothiocyanate is RNCS. In the method, the catalyst is good in chemical selectivity, high in reactivity, mild in reaction condition, and short in reaction time; the reaction has high atom economy and does need a solvent; and the yield of a target product can be up to 99%.

Description

technical field [0001] The invention belongs to the technical field of preparation of sulfur nitrogen organic heterocyclic compounds, and in particular relates to a catalytic preparation method of 2-aminobenzothiazine. Background technique [0002] Sulfur nitrogen organic heterocyclic compounds widely exist in natural bioactive molecules and synthetic drugs. Compounds containing benzothiazine skeletons have been found to have a wide range of physiological activities and are used in sedatives, antihypertensives, antibacterial agents, bactericides, antiproliferative agents, etc. Among them, 2-aminobenzothiazine has a unique Physiological activity has attracted the attention of researchers. [0003] In the prior art, the reported synthetic method of 2-aminobenzothiazine mainly adopts the synthesis of arylamine substituted by halomethyl or hydroxymethyl in the ortho position and sulfur-containing reagents (such as Lawesson reagent, isothiocyanate). reaction. [0004] In 1976,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D279/08B01J31/02
Inventor 徐凡花露黄洁姚志刚
Owner SUZHOU UNIV
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