New Approaches To Heterocycle Synthesis: A Greener Route To Structurally Complex Protonated Azomethine Imines, And Their Use In 1,3-Dipolar Cycloadditions

1-Aza-2-azoniaallene salts are reactive intermediates that undergo [3+2] cycloaddition with many different types of multiple bonds. For the past several years, the Brewer group has studied the reactivity of these intermediates in intramolecular reactions, and have discovered that these cationic heteroallenes can react through a variety of other, mechanistically distinct, pathways to give different classes of nitrogen heterocycles. For example, prior work in the Brewer group revealed that 1-aza-2-azoniaallene salts could react in an intramolecular [4+2] cycloaddition reaction to give protonated azomethine imine salts containing a 1,2,3,4-tetrahydrocinnoline scaffold. Further study of the scope and limitations of this Diels-Alder-like reaction are described herein. These studies primarily focused on how varying the N-aryl ring and alkene substituents affected the reaction. We discovered that in several instances, the metal mediated reaction did not facilitate the cycloaddition very well, so we searched for alternative ways to facilitate the reaction. We discovered that a non-metallic Lewis acid (TMSOTf) provided very clean products with α-chloroazo compounds. I hypothesized that changing the leaving group adjacent to the azo might further improve the reaction. With this in mind, I developed a technique to prepare α-trifluoroacetoxyazo compounds by treating aryl hydrazones with trifluoroacetoxy dimethylsulfonium trifluoroacetate. This technique is compatible with all types of functional groups including nitro aryl compounds, which gave low yields of the corresponding chloroazo derivatives. Importantly, these α-trifluoroacetoxyazo compounds gave even better cycloaddition results when treated with TMSOTf, and this method is more practical, more environmentally friendly, and greener than the metal mediated technique. This process even returned sterically hindered products in high yield, and provide a dearomatized non-protonated azomethine imine salt, which further verified the proposed mechanism of the [4+2] cycloaddition. Azomethine imines are well known to undergo 1,3-dipolar cycloadditions with alkenes. We wondered if the protonated azomethine imine salts generated by the [4+2] cycloaddition could be used in a subsequent base-mediated [3+2] cycloaddition to generate structurally complex tetra- or pentacyclic products. We were pleased to find that the protonated azomethine imines indeed reacted smoothly with a variety of π-system in the presence of triethylamine to give the corresponding cycloadducts in high yields with moderate to high diastereoselectivities. In an attempt to understand the diastereoselectivity of these [3+2] cycloadditions better, I modeled them computationally

Current Situation and Issues of Continuous Assessment System in Mathematics Education of Nepal

Continuous Assessment System (CAS) is a formative type of student assessment carried out during teaching-learning activities in the classroom. The prime concern of this study is to identify the current situation and issues of CAS in the mathematics classroom, and if there are any issues, to indicate some remedies for them. Seventy-nine primary mathematics teachers and nine instructors were selected as samples. The questionnaires, interviews, observations, and focus-group discussions were used as data collection tools. According to the data analysis, most of the respondents mentioned that in teacher training, there is no time for discussion and practical sessions on how to make a plan and use practically CAS tools in students\u27 evaluation, in other words, how to use students\u27 evaluation information to improve their learning. It was also clarified that most teachers do not use CAS evaluation criteria (tools) and give ticks (score) to their students without any real assessment. Thus, they are possibly not able to use the students\u27 evaluation information to improve their learning. For improving the implementation of CAS in the mathematics classroom, teacher training should be practice-based and focused on how to make a plan of CAS and use its tools for students\u27 assessment and how to use assessment information to improve their learning. The government should encourage all teachers to implement CAS in classroom instruction and provide a favorable environment for teachers to share good practices of CAS

A SCENARIO OF MEDIA AWARENESS FOR SOCIAL NETWORKING

The term media is derived from Medium, which means carrier or mode. Media denotes an item specifically designed to reach a large audience or viewers. The term was first used with the advent of newspapers and magazines. However, with the passage of time, the term broadened by the inventions of radio, TV, cinemas and Internet. Tools for social networking and social awareness are developing rapidly and evolving continuously. They are gaining popularity in a growing number of professional as well as personal activities, including scholarly research. There are social awareness tools for science researchers that facilitate collaboration, help manage references, and offer options for presenting findings in new ways.This paper discusses those tools. Evaluating and understanding their functionalities requires effort, and scientists can be reluctant to invest the necessary time to learn to use and populate them on their own. This suggests that an important role for librarians is to evaluate the many social awareness tools available, to recommend the ones that are best suited to each researcher's needs, and to help researchers use those tools effectively.In the world of today, media has become almost as necessary as food and clothing. It is true that media is playing an outstanding role in strengthening the society. Its duty is to inform, educate and entertain the people. It helps us to know current situation around the world. The media has a strong social and cultural impact upon society. Because of its inherent ability to reach large number of public, it is widely used to convey message to build public opinion and awareness

Early English travellers in India: a study in the travel literature of the Elizabethan and Jacobean periods with particular reference to India

The narratives of travel and exploration written by the English voyagers and merchant adventurers who visited India during 1579 -1630 are of great literary and historical value for many reasons. For the first time they brought the ordinary Englishman in contact with the peoples of the East and made it possible for tradesmen to see through the mind's eye new and unlooked -for splendours in the Indies, the glamour of the Mughal court, or the power of the Great Turk. The common man found in the narratives of travel not only a romantic literature more fascinating than fiction, but a call to personal adventure. These were the stories, not of King Arthur or of fabulous knights, but of men who had lived and had their being in Elizabethan England. To any apprentice might come adventures that would have dazzled even Guy of Warwick -, as Captain John Smith2 himself had witnessed. Nor was rhetorical decoration needed to adorn these tales. The plain narratives were sufficiently attractive without adornment. No one has yet appraised the influence on modern English prose of the matter -of -fact relations of the voyagers; but merely as evidence of the development towards verbal simplicity many of these accounts deserve the study of literary historians. Out of utilitarian works on geography and the homespun narratives of merchants and seamen grew a vast literature, perhaps more completely than any other inspired by and appealing to the middle class. For the modern reader, these narratives not only throw considerable light on one of the most crucial periods of Indian history, but also reveal the beginnings and gradual growth of English power in the East. Compiled by men to whom everything in India was new and strange, they form a valuable supplement to the records of the native chroniclers; for the latter took for granted many local institutions and customs unfamiliar to Europeans, and all too often sacrificed objectivity to eulogies of the reigning sovereign.The number of English visitors to India during this period was remarkably large, and for this reason, detailed examination of all of them is outside the scope of such a study as this. In order to avoid swelling the dimensions of this already lengthy work to unreasonable proportions, I have omitted all but a few absolutely important travellers and have employed the word 'traveller' to signify only those who left extensive records of their experiences in India. Amongst them, how - ever, I have included, at the very outset, a Jesuit who is hardly a traveller except in an extended sense of the word, since no account of the early British transactions in the East can be deemed complete unless some notice is taken of this pioneer of British `gravel to India. The importance of Fr. Stephens (for this was the name of the Jesuit in question), which has led me to devote one full chapter to him, will be sufficiently clear in the following pages, but the particular circumstance which has made his inclusion imperative is the fact that he is little known in this country, whereas he deserves to be much better known by his countrymen, perhaps as well known as some of the distinguished poets of the sixteenth and seventeenth centuries or the Orientalists of later ages.From what we have seen..., it is clear that although there were notions current about Indian people, Indian traits, Indian climate, long before there was any regular contact between England and India, precise information about the latter began to find its way into Europe after the discovery of the Cape route, and into England after the return of the British pioneers, such as Ralph Fitch, Newberry, etc. The modern European knows much about India, and in this sense at least these early travel -accounts may appear to be outdated; but their importance lies in the fact that they throw considerable light on the India of the great Mughals and that their writers had a certain advantage over the chroniclers of the court. Having nothing to fear or to expect from the powers that were, they could fearlessly tell the unvarnished truth regardless of official frowns or favours. Having come from other lands, they recorded with meticulous care matters seemingly unimportant which a native of India would ordinarily have dismissed as commonplace. Moreover, their narratives and journals have been drawn upon by English poets and prose- writers, some of whom read them extensively and thus broadened and enriched both their knowledge of the world and their general outlook on life. Through these accounts accessions were made to the English language of many Hindi, Arabic and Persian words.It is these travellers, sailors and sea- captains who ask us Indians not to be led too far astray by complacent dreans of the days of glory that are no more, but to see and realize our most degrading varieties of superstition, our most grotesque forms of idolatry. They had no desire to hide things. They spoke more plainly than we do, and far more strongly, and they believed, as we do, that what we think of ourselves is not necessarily what the world thinks of us

A Simple Approach for Black Out Problem

Antennas surrounding by the plasma medium does not radiate for all the frequencies but only for those which are greater than the plasma frequency. Here we have proposed a cylindrical (axial magnetized) antenna system which radiates for all frequencies irrespective of plasma frequency and this is the solution for the black-out situation which occurs for certain frequencies