A New MappingExploration Approach for HT Synthesis of Zeolites

1 3J IRAN CHEM SOCDOI 10.1007/s13738-014-0542-3ORIGINAL PAPEROne-pot synthesis of 1,2,4-oxadiazoles from carboxylic acids using 4-(dimethylamino)pyridinium acetate as efficient, regenerable, and green catalyst with ionic liquid characterNajmeh Nowrouzi · Dariush Khalili · Maryam Irajzadeh

Received: 31 May 2014 / Accepted: 29 September 2014 © Iranian Chemical Society 2014The 1,2,4-oxadiazole scaffold is a class of heterocycle commonly found in biologically active molecules. This motif is often used as an amide or ester bioisostere and is found in several drugs and drug leads that may potentially act as serotonergic (5-HT3) antagonists, tyrosine kinase inhibitors, monoamine oxidase inhibitors, aldose reduc-tase inhibitors, metabotropic glutamate subtype 5 (mGlu5) receptor antagonists, muscarinic agonists, and S1P1 ago-nists. Therefore, they have received considerable attention in the drug discovery programs and development of clean, safe, effective, economical, and high-yielding synthesis routes is still desirable and is in demand [6–11]. Several methods have been reported in the literature for the synthe-sis of these useful heterocycles [12–16]. Most commonly, 1,2,4-oxadiazoles are synthesized from amidoximes and carboxylic acid derivatives in two steps. During the first step, the amidoxime prepared by the addition of hydroxy-lamine to a nitrile compound is O-acylated by an activated carboxylic acid derivative. The heterocycle is subsequently formed by intramolecular cyclodehydration. Cyclization of the O-acyl amidoxime is generally the most difficult and time-consuming step and often requires multi-step pro-cedures, exhaustive reflux conditions in DMF or pyridine and the use of a strong base [17]. Activated carboxylic acid derivatives used for the O-acylation step include ester [18], orthoesters [15], acid chlorides [19], and anhydrides [20]. The use of carbodiimides such as EDC, CDI, and DCC for the in situ activation of carboxylic acids has been also pre-viously published [21, 22]. These methods, however, suf-fer from several drawbacks. Toxicity, high reactivity of acid chlorides, difficult storage and handling, as well as limited commercial availability of acid chlorides are major disad-vantages of using these chemicals for synthetic purposes. In addition, carboxylic acids need a coupling reagent such as DCC, EDC, CDI, TBTU, HOBt, or HBTU to react with Abstract A recyclable bifunctional acid–base organo-catalyst with ionic liquid character has been prepared and its catalytic activity for the preparation of oxadiazoles has been investigated.Keywords Oxadiazoles · Ionic liquid · Organocatalyst · Multi-component reaction · 4-(N,N-Dimethylamino)pyridineIntroductionMulti-component reactions (MCRs) have emerged as an attractive and powerful strategy for organic synthesis com-pared to multi-step reactions due to the creation of several new bonds in a one-pot reaction, low number of reaction and purification steps, selectivity, synthetic convergence, high atom economy, simplicity, and synthetic efficiency. Therefore, academic and industrial research groups have increasingly focused on the use of MCRs to synthesize a broad range of products. In fact, development of MCRs can lead to new efficient synthetic methodologies to afford many small organic compounds in the field of modern organic, bioorganic, and medicinal chemistry [1–5].Electronic supplementary material The online version of this article (doi:10.1007/s13738-014-0542-3) contains supplementary material, which is available to authorized users.N. Nowrouzi (*) · M. Irajzadeh Department of Chemistry, Faculty of Sciences, Persian Gulf University, Bushehr 75169, Irane-mail: nowrouzi@pgu.ac.irD. Khalili Department of Chemistry, Shiraz University, Shiraz 71454, Iran J IRAN CHEM SOC

人教版英语九年级全一册第五单元

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Title: My Unforgettable Summer Vacation

Hi there! My name is Emma, and I'm a 9-year-old student

who just finished third grade. I can't wait to share with you the

exciting adventures I had during my summer vacation. It was

truly an unforgettable experience!

As soon as the school year ended, my parents surprised me

with the news that we would be going on a trip to the

countryside. I was thrilled! Living in the city, I don't get many

opportunities to explore the great outdoors, so this was a dream

come true.

We packed our bags and set off on a long drive to a small

village nestled in the mountains. The scenery along the way was

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wildflowers. I couldn't help but press my face against the car

map作文英语

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Map is a powerful tool that helps people navigate the world

around them. These visual representations of geographical areas

provide to-scale representations of locations, features, and

distances, making it easier for us to understand where we are

and where we are going. In this essay, I will discuss the

importance of maps, their evolution over time, and the impact

they have on our daily lives.

Maps have been used for thousands of years to help people

navigate the world. The earliest known maps date back to

ancient Babylon in around 2300 BC. These early maps were

simple drawings on clay tablets, but they served the same

purpose as modern maps – to help people understand the world

around them. Over time, maps have evolved to become more

detailed and accurate, with the introduction of technologies such

发展太空科技的优点英语作文80词

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The Benefits of Developing Space Technology

Hi everyone! Today, I want to talk about the benefits of

developing space technology. It's super cool!

Firstly, space technology helps us explore the universe. We

can send rockets and satellites into space to learn about planets,

stars, and even black holes. It's like being an astronaut without

leaving Earth!

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predict natural disasters.

Lastly, space technology brings us new inventions and

discoveries. It helps scientists develop new materials, medicines,

and technologies that make our lives better. Who knows, maybe

one day we'll have vacations on the Moon! In conclusion, developing space technology is amazing! It