Silica chloride catalyzed efficient route to novel 1-amidoalkyl-2-naphthylamines under sonic condition in waterUltrasonics Sonochemistry

About

Authors
Bandita Datta, M.A. Pasha
Year
2013
DOI
10.1016/j.ultsonch.2012.06.008
Subject
Radiology Nuclear Medicine and imaging / Chemical Engineering (miscellaneous) / Acoustics and Ultrasonics

Text

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Silica chloride nt c 35 k ndi vol s) have synthe d pro e appro , drugg to op workup is easier [4].

The amide group is an essential building block for numerous natural products, synthetic pharmaceuticals, and a wide variety of biologically active compounds [5]. As a consequence; the development of general methods for the synthesis of amide derivatives has been the subject of considerable synthetic efforts and still requires attention. Amide moiety has been involved in many reactions like Ugi [6] and Passerini reactions [7]. Furthermore, the scope of this pharmacophore has been increased by the identificaThere has been growing recognition that water is an attractive medium for many organic reactions [14] and many MCRs in aqueous medium have been reported [15]. However, to the best of our knowledge, we are the first ones to report the present synthesis of amidoalkyl-2-naphthylamine derivatives under aqueous sonic condition. As a consequence of our interest in the aqueous medium organic synthesis [16a] and our continual work on the synthesis of biologically important molecules [16b,c]. We investigated a first three-component one-pot synthesis of 1-amidoalkyl-2-naphthylamines from 2-naphthylamine in the presence of silica-chloride ⇑ Corresponding author. Tel.: +91 80 22961337; fax: +91 80 22961331.

Ultrasonics Sonochemistry 20 (2013) 303–307

Contents lists available at o .e lE-mail address: mafpasha@gmail.com (M.A. Pasha).covery [2]. In a true sense, MCRs represent environment friendly processes by reducing the number of steps, energy consumption and waste production.

The application of ultrasound in organic synthesis has been increasing because of its advantages including shorter reaction times, milder reaction conditions and higher yields in comparison to classical methods [3]. Since in this technique the reaction is carried out normally at lower external temperature relative to the usually thermal methods, the possibility of occurrence of undesired reactions is reduced, and as a result of cleaner reaction the novel amidoalkyl-2-naphthylamine derivatives from aromatic aldehydes, 2-naphthylamine and acetamide.

The need to reduce the amount of toxic waste and byproduct arising from chemical process requires increasing emphasis on the use of less toxic and environmentally compatible materials in the design of new synthetic methods [12]. One of the most promising approaches is use of water as a reaction medium. Breslow, who showed that hydrophobic effects and polarity effect could strongly enhance the rate of several organic reactions, rediscovered the use of water as a solvent in organic chemistry in the 1980s [13].Water

Ultrasound 1. Introduction

Multicomponent reactions (MCR recent years owing to exceptional atom economy, high selectivity, an

These reactions constitute a valuabl large libraries of structurally related by enabling identification and leadin1350-4177/$ - see front matter  2012 Elsevier B.V. A http://dx.doi.org/10.1016/j.ultsonch.2012.06.008drawn high efforts in tic efficiency, intrinsic cedural simplicity [1]. ach for the creation of like compounds, theretimization in drug distion of these molecules as the precursors of aminoamides which find application in the synthesis of dendrimers [8]. Aminoamides can also be used in the synthesis of metal complexes [9] and could be employed as adjuvents for drugs [10]. Derivatives of aminoamide have also been shown to have antioxidant and anti-inflammatory properties [11]. In view of this we have synthesized some2-Naphthylamine

AcetamideSilica chloride catalyzed efficient route to under sonic condition in water

Bandita Datta, M.A. Pasha ⇑

Department of Studies in Chemistry, Bangalore University, Central College Campus, Ben a r t i c l e i n f o

Article history:

Received 30 January 2012

Received in revised form 15 June 2012

Accepted 19 June 2012

Available online 28 June 2012

Keywords:

Aldehydes a b s t r a c t

A one-pot three-compone achieved by sonication at protocol afforded correspo high yields. The method in

Ultrasonics S journal homepage: wwwll rights reserved.ovel 1-amidoalkyl-2-naphthylamines u, India ondensation of an aldehyde, 2-naphthylamine, and acetamide has been

Hz. The reaction is catalysed by silica chloride in aqueous medium. This ng 1-amidoalkyl-2-naphthylamines in shorter reaction durations, and in ves simple work-up procedure, and avoids use of hazardous reagents.  2012 Elsevier B.V. All rights reserved.

SciVerse ScienceDirect nochemistry sevier .com/locate /u l tson

Sonas a catalyst under aqueous sonic condition as shown in the

Scheme 1. 2. Methods 2.1. Materials and instruments

All starting materials were commercial products, and were used without further purification, except liquid aldehydes which were distilled before use. Yields refer to yield of the isolated products.

Melting points were measured on a RAAGA, Indian make melting point apparatus. Nuclear magnetic resonance spectra were obtained on a 400 MHz Bruker AMX instrument in DMSO-d6 using

TMS as a standard. LC–mass spectra were performed on an Agilent

Technologies 1200 series instrument. HRMS analyses were carried out using ESI-Q TOF instrument. Infrared spectra were recorded using Shimadzu FT-IR-8400s spectrophotometer as KBr pellets.

All the reactions were studied using SIDILU, Indian make sonic bath working at 35 kHz (constant frequency, 120 W) maintained at 28 C without mechanical stirring. Silica chloride was prepared using the reported method [17]. 2.2. General procedure for the synthesis of 1-amidoalkyl-2naphthylamines

Aromatic aldehyde (5 mmol), 2-naphthylamine (5 mmol), acetamide (5 mmol) and silica chloride (100 mg) was added to water (5 mL) in a 25 mL RB flask and irradiated in an ultrasonic bath.

After completion of the reaction ethyl acetate (10 mL) was added and the catalyst was filtered, washed with warm ethanol and dried for reuse. The filtrate after distilling the solvent was dried under vacuum to afford the crude product. The pure product was obtained after silica gel column chromatography (30% EtOAc). All the products were characterized by the IR, 1H NMR, 13C NMR and