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Transition Metal-Catalyzed Borylation of Aromatics

Thesis Info

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Author

Shahzadi, Hafiza Tayyaba

Program

PhD

Institute

Lahore University of Management Sciences

City

Lahore

Province

Punjab

Country

Pakistan

Thesis Completing Year

2019

Thesis Completion Status

Completed

Subject

Chemistry

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/11470/1/Hafiza%20Tayyaba%20Shahzadi%20chemistry%202019%20lums%20lhr.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727630408

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Selective functionalization of hydrocarbons represents a long-standing challenge in the synthetic world. Transition metal-catalyzed reactions, such as transformation of C–H/ C– X bond to C–B bond has emerged as potent tool towards this goal during the last few decades. Especially the Ir-catalyzed aromatic C-H activation/borylaytion provides unique selectivity which is complemantary to those found in the traditional synthetic routes. Sterically governed regioselective control in this new synthetic tool allows the synthesis of (hetero)aromatic compounds which are difficult to access by the conventional routes. In the current work, we have utilized this methodology to gain facile access to new aromatic building blocks with better atom & step economy. One study presents the synthesis of hydroxybenzoates. Hydroxybenzoates are widely used as preservatives and antiseptics in the food and pharmaceutical industry. However, strategies focusing on the direct synthesis of 2,6- and 2,3-disubstituted hydroxybenzoates are lacking in literature. Herein we report an efficient protocol employing iridium-catalyzed C–H borylation/oxidation of commercially available benzoic acid/ester substrates. This route provides facile access to halogen decorated para-/meta-hydroxybenzoates as the synthesis of akin compounds is laborious by traditional approaches. Second project targets the synthesis of boscalid analogs. Boscalid is an extensively used fungicide for crop protection. Traditional routes of boscalid synthesis involve precursors that need pre-functionalization of arenes, which affects the step economy and overall efficiency. The aim of this study is to develop boscalid analogues from readily available hydrocarbon feedstock without pre-functionalization. Sequential Ir-catalyzed C–H borylation of arenes and Suzuki coupling provide biphenyl amines which on amidation produce boscalid analogues in good yield. Synthesized compounds are further evaluated by molecular docking to gain insight into the binding pocket of protein. The In-vitro studies of the analogs are carried out against Fusarium moniliforme and few of the synthesized compounds provided superior inhibition on potato dextrose agar (PDA) plates. Next, Ir-catalyzed C-H borylation of CF3 substituted pyridines is reported. The versatility of the methodology is demonstrated by the use of various substitution patterns in the substrate molecule. Based on the steric evaluation, selective positions of CF3 substituted pyridines are functionalized. Several functional groups like halo, ester, methoxy and amino are compatible with this methodology. Chiral boronic esters are indispensable building blocks owing to their versatile transformations and immense applications in medicinal and material chemistry. Herein, we also disclose Pd-catalyzed chiral borylation of aryl halides, whereby numerous substrates bearing broad range of functional groups are found to be compatible for the developed approach. Aryl/hetero aryl chiral boronic esters are obtained in moderate to excellent yield. The resulting chiral boronic esters can serve as significant precursors in asymmetric synthesis.
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مبشر سعید

کوئی ملتا ہی نہیں سوختہ پا میری طرح
جس کو معلوم ہو وحشت کا پتا میری طرح
میرے جیون کو اُداسی سے ملانے والا!
دشت میں پھِرتا رہے آبلہ پا میری طرح
میں نے احباب کو آواز لگا کر پوچھا
کوئی رہتا ہے شبِ غم میں سدا، میری طرح؟
اے کئی دن سے مرے ذہن پہ چھائے ہوئے شخص
تو مجھے وصل کے سپنے نہ دکھا میری طرح
رات بھر چاند کو احوال سنانے کے لیے
کیا ٹھہرتی ہے دریچوں میں ہوا، میری طرح؟
زندگی! میری طرف دیکھ کے ایماں سے بتا
ایک بھی شخص کوئی تجھ کو مِلا، میری طرح
تند اور تیز ہواؤں کے علاقے میں سعید
زیست کرتا ہے فقط دل کا دِیا میری طرح

Al-Sukākī’s Classification of Metaphor and Qurānic Discourse

The present study is divided into two main sections; the first section will give a general overview about the figurative language and more focus on metaphor (istiᶜārah in Arabic) because the metaphor is considered as one of the most literary devices and the main category of the figurative language. So in this study has given various definitions of figurative language and metaphor according to Muslims and Non-Muslims linguists and along with this explained Al-sukākī’s classification of metaphor which is little close to Al-Jurjānī’s classification of metaphor and view respectably among Muslims and Non-Muslims linguists. The second section of this study deals with metaphors given in Holy Qur'ān, which are denoted according to Al-sukākī’s classification in this respect. In this reference the verses are presented with detailed tafsīrī literature so the reader could well comprehend the purposes and the classical aspect of metaphors in text and also could evaluate linguistic architecture of  Holy Qur'ān.

Metal-Microbe Interaction in Municipal Solid Waste Compost Amended Soil and its Effect on Maize Zea May L. Growth

The use of municipal solid waste compost (MSWC) can be very helpful in agricultural soils because of its associated useful characteristics. It improves soil physico-chemical properties, soil microbial biomass (SMB), mitigates soil diseases and enhanced soil organic matter (SOM) etc. However, the threat related to toxic heavy metal presence in MSWC can limit its extensive use as a soil amendment in agriculture. Higher heavy metals concentrations can decrease SMB, soil microbial ecology and activities of enzymes etc. The microbial processes affect transformation of metals which influence the availability of these metals in soil. The microbiological processes can either solubilize metals which may result in their potential toxicity and bioavailability or immobilize them. A lot of work has been done on the effect of toxic heavy metals on soil microorganisms, however, the research work is mainly experimented in acidic soils. The data regarding metal–microbe interaction in alkaline calcareous soils amended with MSWC is very limited. A study was planned to evaluate the effect of heavy metals present in MSWC on SMB and how soil microorganisms (Enterobacter sp. MN-17 (ST1) and Bacillus sp. MN-54 (ST2)) transform cadmium (Cd) and lead (Pb). The effect of MSWC on heavy metals availability, and growth of maize (Zea mays L.) was studied. The role of biochar and metal tolerant bacterial strain (MN-17) was also assessed to reduce metal availability in MSWC amended soils. Results showed that the increase in MSWC rate from 5 to 20 t ha-1 significantly increased the SMB (C and N) and soil dehydrogenase activity (DHA). MSWC application at 20 t ha-1 showed highest values of SMB C (21 %), SMB N (111 %) and DHA (25%) over control. No negative impacts were observed on the soil quality indicators by applying higher rates of MSWC during the whole incubation period. The addition of metal tolerant strains (MN-17 and MN-54) showed significant difference in reducing the exchangeable fraction of Cd and Pb in MSWC amended soil. Soil microbial biomass C and N and soil dehydrogenase enzyme concentrations were also increased by the addition of metal tolerant strains in MSWC. It was noticed that the metal tolerant bacterial strains can affect the mobility of metals through microbial transformation in soil and can reduce the exchangeable fraction of heavy metals in MSWC amended soil. Furthermore, roots of maize plants showed the highest metal concentrations which might act as a barrier for Pb, resulting in reduced concentrations of Pb in shoot of maize. However, the uptake of Cd remained higher from roots to shoots in maize vii plant. MSWC showed a positive impact on the plant growth and physiological parameters. Soil quality parameters (SMB and DHA) were also enhanced in soil where maize plants were grown upon the application of MSWC. In addition, poultry manure biochar and metal tolerant strain MN-17 and their combination remained more effective in the immobilization of Cd (66%) and Pb (61%) in MSWC amended soil. The mixing of biochar and metal tolerant strain MN-17 alone and their combination with MSWC showed better growth and physiological parameters as compared to the plants grown in MSWC amended soil. Soil microbial biomass C and N and soil dehydrogenase enzyme concentrations were also increased by the addition of biochar and MN-17 in MSWC amended soil. With incorporation of MSWC in soil, no detrimental effects of heavy metals on maize plant growth and soil microbial biomass were found. However, due to the high bioavailability potential of Cd and Pb, the repeated applications of MSWC would carry a risk of Cd and Pb build-up in soil.