Regioselective N-alkylation of 2-aminobenzothiazoles with benzylic alcohols

Li, Feng; Shan, Hongyan; Kang, Qi‐Kai; Chen, Lin

doi:10.1039/c1cc10604j

Cited by 64 publications

(29 citation statements)

References 30 publications

(2 reference statements)

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“…The synthesized 2-aminobenzothiazoles were further treated with alcohol in the presence of Conc. H 2 SO 4 and ILs to form corresponding N-alkylated substituted benzothiazoles [12][13] (4a-b). In other reaction substituted benzothiazoles were treated with aldehyde (Aromatic and heteroaromatic) to form corresponding Schiff bases [14][15] (5a-b).…”

Section: Resultsmentioning

confidence: 99%

Untitled

2017

IJPSR

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ABSTRACT:The 2-aminobenzothiazole moiety and its derivatives have immense importance in medicinal and pharmaceutical chemistry as a potent biologically active molecules. The synthesis of 2-aminobenzothiazole derivatives carried out from substituted phenyl thiourea which is synthesized by substituted aniline in ionic liquid (1-butyl-3-methylimidazolium) bisulphateFurther N-alkylation at amino group of synthesized 2-aminobenzothiazoles was carried out with alcohol using conc. H 2 SO 4 and Schiff bases are also prepared by reaction of substituted 2-aminobenzothiazoles and aromatic aldehydes. ILs are green alternate of volatile organic solvents and they are beneficiary environmentally and economically. The reactivity, reaction rate and yield were enhanced by using ILs and the products were recovered by simple filtration. 2-Nalkylaminobenzothiazoles and Schiff base derivatives are very important structural units in many medicinal compounds. The synthesized compounds can show many biological activities like antitumor, antimicrobial and anti analgesic. The characterization of synthesized compounds was done by elemental and spectral analysis.

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Section: Resultsmentioning

confidence: 99%

Untitled

2017

IJPSR

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“…To promote the N‐alkylation using ROH, metal‐based catalyses have been developed. These reactions mainly use benzylic‐type and saturated alcohols with catalytic Ru,3 Ir,4 Cu,5a–e Ni,5f and Ag5g,h species. In addition, Lewis acidic metals6 and Pd7 catalysts are also competent mediators of N‐alkylation with benzylic‐type secondary alcohols and allylic alcohols.…”

Section: Methodsmentioning

confidence: 99%

Selective N‐Alkylation of Amines with Alcohols by Using Non‐Metal‐Based Acid–Base Cooperative Catalysis

Oishi

Saitō

2011

Chemistry A European J

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Higher amines are widely used in both the bulk and fine chemical industry for the synthesis of fundamental materials, such as additives, dyes and agrochemicals.[1] Therefore, the development of a selective N-alkylation method that is cost effective, salt free and environmentally benign is of considerable interest. Indeed, reactions involving the N-alkylation of amines with alcohols [2] (R À OH) in place of R À X, where X denotes halide, tosylate, mesylate, or triflate, [1d,e] are well documented. To promote the N-alkylation using RÀOH, metal-based catalyses have been developed. These reactions mainly use benzylic-type and saturated alcohols with catalytic Ru, [3] Ir, [4] Cu, [5a-e] Ni, [5f] and Ag [5g,h] species. In addition, Lewis acidic metals [6] and Pd [7] catalysts are also competent mediators of N-alkylation with benzylic-type secondary alcohols and allylic alcohols. Herein, we report a novel and straightforward method for the N-alkylation with R À OH (18, 28 and 38) using non-metal-based [8a] catalysis promoted by 1,3,5-triazo-2,4,6-triphosphorine-2,2,4,4,6,6-hexachloride [9] (TAPC). This new reaction involves substitution (S N ) at the alcohols sp 3 carbon atom bearing the hydroxyl group (Scheme 1), [8b] by which selective N-mono-and dialkylation were successfully achieved.Treatment of aniline (1 a, 2 equiv) with benzyl alcohol (2 a, 1 equiv) in the presence of TAPC (5 mol % with respect to 2 a) at 160 8C for 12 h in 1,2,4-trimethylbenzene (1,2,4-TMB) under Ar using a sealed reactor, [10] followed by column chromatography on silica gel, gave mono-alkylated amine 3 aa in 92 % yield (Scheme 2, Table 1, entry 1).[11] The tertiary amine resulting from N-dialkylation was obtained in about 7 % yield, as determined by GC-MS and 1 H NMR spectroscopy. Formation of benzyl chloride and dibenzyl ether was found to be negligible [12] by GC-MS analysis. In the absence of solvent, the yield of 3 aa decreased to 75 % (entry 1). Addition of water (0.3 and 2.0 equiv with respect to 2 a) to the solute at 25 8C prior to reaction initiation did not prevent the reaction from proceeding at 160 8C (3 aa was recovered in 98 and 90 %, respectively). Finally, a change in the ratio of 1 a/2 a from 2:1 to 1:2.5 resulted exclusively in N-dialkylation, giving 4 aa in 80 % yield (entry 2). [13] Control reactions were performed to probe the involvement of Brønsted acid catalysts that might be generated in [a] Dr.

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“…For the syntheses various approaches have been proposed and developed . The so called borrowing hydrogen method, consisting in an alcohol based alkylation, is a very promising approach for the synthesis of secondary amines attracting recently great attention ,,. Indeed, it is an atom‐economic and environmental friendly approach, as alcohols are abundant and water is the only by‐product.…”

Section: Introductionmentioning

confidence: 99%

“…Also, heterogeneous catalysis has been explored , Heterogeneous catalysts containing metals such as Pd, Ru, Au, Ag and Fe, have been used for N‐alkylation of amines with alcohols. However, they require multistep and complex procedures and often result in reduced activity and selectivity.…”

Section: Introductionmentioning

confidence: 99%

Self‐Suspended Nanoparticles for N‐Alkylation Reactions: A New Concept for Catalysis

2019

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The catalytic activity of snowman‐like and core‐shell Fe3O4/Au nanoparticles (NPs), obtained through a “wet chemistry” approach which directly restitutes nanocatalysts stable and highly active in the reaction medium, was tested towards N‐alkylation reactions. The nanocatalysts were tested for the synthesis of secondary amines. The core‐shell NPs, thanks to the surface properties, homogeneous dispersion and intimate connection with reagents in the catalyst medium, exhibited an excellent catalytic activity (e. g. >99 % yield and conversion of aniline in very short time and mild conditions). Owing to the magnetic part, the nanoparticles can be easily separated and reused, showing an almost stable activity after 10 cycles.

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Regioselective N-alkylation of 2-aminobenzothiazoles with benzylic alcohols

Abstract: The preparation of 2-(N-alkylamino)benzothiazoles via regioselecive N-alkylation of 2-aminobenzothiazoles has been accomplished by using benzylic alcohols as alkylating agents.

Cited by 64 publications

References 30 publications

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Selective N‐Alkylation of Amines with Alcohols by Using Non‐Metal‐Based Acid–Base Cooperative Catalysis

Self‐Suspended Nanoparticles for N‐Alkylation Reactions: A New Concept for Catalysis

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