Arylboronic acids & esters are versatile synthetic intermediates used extensively in the synthesis of existing as well as new medicines, agrochemicals, conjugated polymers, and variety of other functional materials. One of the most common and well-known application of aryl boronic esters in organic syntheses is in the Suzuki cross coupling reaction (Chemistry Nobel Prize 2010). Due to large number of applications of aryl boronic esters, there is huge interest in the development of new & convenient routes for their syntheses. Traditionally aryl boronic esters have been prepared from aryl halides by generating organometallic species (organolithium or magnesium) followed by treatment with trialkyl borate. In 1995, Miyaura and co-workers reported a direct palladium catalyzed borylation of aryl halides which by-passed the need to prepare organolithium/magnesium compounds. More recently, groups of Smith-Maleczka and Hartwig- Miyaura have reported a new iridium-catalyzed route for the syntheses of aryl boronic esters directly from the hydrocarbon feed-stock. Chapter 1 describe the literature background about this methodology. While Chapter 2-4 summarize our efforts to synthesize fluorinated aryl & pyridylboronic esters using the newly developed iridium-catalyzed C–H borylation reaction. Fluorinated molecules are becoming increasingly popular in the pharmaceutical and agrochemical industries. This is due to the fact that strategically placed fluorine atoms often have a positive influence on the biological properties of active compounds. Fluorine atom as well as fluorine containing substituents such as triflouromethyl or flouroalkoxy groups are useful to tailor pKa values, help penetrating the cell membrane, and are stable to oxidative metabolism. About 20% of all pharmaceuticals and about 30% of agrochemicals under development or recently introduced on the market contain fluorine. Selected examples of fluorine containing drugs include Lipitor, Celebrex, Ciprofloxacin, Pantoprazole, and Fluoxetine etc. Consequently, synthetic methods for the selective preparation of specifically fluorinated intermediates and building blocks are of high importance. Chapter 2 describe our efforts to synthesize fluoroalkoxy substituted arylboronic esters by iridium-catalyzed aromatic C−H borylation. The fluoroalkoxy groups employed include trifluoromethoxy, difluoromethoxy, 1,1,2,2-tetrafluoroethoxy, & 2,2-difluoro- 1,3-benzodioxole. Regioselectivities observed in iridium-catalyzed borylation of fluoroalkoxy arenes are complementary to those observed for electrophilic aromatic substitution and directed ortho metalation. 2,6-bis(trifluoromethyl) pyridine is a highly electron deficient heteroaromatic compound. Attempted functionalization of the C–H bonds of 2,6-bis(trifluoromethyl)pyridine using the traditional methodologies has not been successful. Electrophilic aromatic substitution is not possible due to the highly electron deficient nature of 2,6-bis(trifluoromethyl)pyridine. Literature search showed that attempted directed ortho metalation on this compound using butyllithium or tert-butyllithium has also not been successful. In Chapter 3, it has been shown that iridiumcatalyzed aromatic borylation can readily functionalize this substrate to yield 2,6- bis(trifluoromethyl)pyridine-4-boronic acid pinacol ester. The newly synthesized highly electrondeficient pyridine-4-boronic ester was employed in Suzuki coupling reaction using various (hetero)aryl bromides and the coupled products were obtained in good to excellent isolated yields. Double, and triple Suzuki coupling reactions of the pyridyl-4-boronic esters were also successful. These coupling reactions demonstrate that this new pyridine-4-boronic ester can be very useful for the incorporation of one of the strongest electron-withdrawing fluorinated aromatic group in organic materials. Chapter 4 describe our results on the borylation of unsymmetrical 2,6-di-substituted pyridines. Regioselective borylation on the 4-position of various 2,6-di-substituted pyridines was generally observed as expected based on steric effects. The only major exception being the 2,6-dimethoxypyridine in which significant amount of borylation ortho to the methoxy groups were also observed. Erosion in regioselectivity for this substrate was removed by lowering the reaction temperature. In conclusion, iridium-catalyzed aromatic C–H borylation is a convenient tool to functionalize fluoroalkoxy arenes and pyridines, allowing new regioselectivity patterns which are not available through the traditional routes. Synthetic utility of the newly synthesized pyridyl & arylboronic esters is demonstrated by using these in the Suzuki coupling reaction.
میرااستاذ دنیا کے اندر مختلف نسل، مختلف قوم، مختلف مذاہب ،مختلف رنگ اور مختلف نظریات کے لوگ رہائش پذیر ہیں، ہر ایک اپنے اپنے نظریے، اپنے اپنے مذہب ، اپنے اپنے رسم و رواج اور اپنے اپنے طریقہ کار کے تحت ایام ِزیست گزار رہا ہے ، معاشرے میں فلاحی ورکر کا اپنا کردار ہے، اسمبلی کے ممبر کا اپنا کردار ہے، کرسی عدالت پرمتمکن منصف ذیشان کا اپنا کردارہے، ایماندار تا جر کا اپنا کردار ہے، ہنر مند فنکار کا اپنا کردار ہے، دولت مند ساہو کا رکا اپنا کردار ہے، ہوشمند اداکار کا اپنا کردار ہے، سرحدوں کے محافظ کا اپنا کردار ہے ، تہجد گزار عابد کا اپنا کردار ہے، اطاعت گزار ساجد کا اپنا کردار ہے، جامع مسجد کے خطیب کا اپنا کردار ہے، اچھے مصنف اور ادیب کا اپنا کردار ہے،’’ یعنی ہر گُلِ را رنگ و بوئے دیگر است‘‘ ہر پھول کی خوشبو اور رنگ علیحدہ علیحدہ ہے لیکن ان میں جس بات پر اتفاق ہے وہ یہ ہے کہ کوئی ذوی العقول اور حیوان ناطق ایسانہیں کہ جس کا کوئی نہ کوئی استاد نہ ہو کوئی رہبر ورہنماء نہ ہو، کوئی ہادی ومرشد نہ ہو!۔ شومیکر اگر جوتا بنا تا ہے تو اس میں بھی کسی استاد کا ہاتھ ہے، ٹیکسٹائل مل کا مالک اگر کپڑابنتا ہے تو وہ بھی استادکا مرہونِ منت ہے، تا جر ہو یا صنعت کار ، پٹواری ہو یاتحصیلدار ، اکاؤنٹنٹ ہو یا بینکار ، مزارع ہو یا جاگیردار ، زمیں پر چلنے والا ہو یامحو پرواز یہ سب کے سب ٹیچر اور مدرس کے لگائے ہوئے نخل ہیں جواب سروقد ہو چکے ہیں۔ ان سے جہالت اور بے علمی کے خس و خاشاک کو صاف کر کے محنت اور مشقت کا پانی دے کر پروان چڑھانے والی اگر اللہ تعالیٰ کے بعد کوئی ذات...
The study aims to assess liquidity risk of Islamic banking sector with Islamic banks performance working under Sharia jurisdictions. To deduct this six Islamic banks are selected of Pakistan by deploying regression analysis on panel data. Simple random sampling is used to select these banks to assess liquidity risk management tools of study. For performance profitability index is used generated by ROA, ROE and EPS. Thus the results inferred that liquidity risk proponents have significant role on bank performance and there is dire need to focus risk management compliance practices and regulations by these banks to reduce banks financial disparity. The value of study is in itself that has less focused in previous studies revealing its originality.
Islam differentiates between lending (qarḍ ḥasan) and investing (on profit and loss sharing basis), former with capital guaranteed but with zero interest, and latter based on sharing in profit and loss. Since its inception 40 years ago in the world and in Pakistan (in 1980s), extensive efforts have been made to bring the Islamic banking in total conformity with the principles of Sharīʿah. The theoretical models, on which the contemporary Islamic Banking evolved, mainly contained Muḍārabah & Mushārakah (i.e. based on participatory systems), Murābaḥah & Ijārah (i.e. debt based) and Salam and Istiṣnāʿ (i.e. deferred payment sale or manufacturing contracts). In practice, however, Islamic banking substantially drifted towards debt-based financings (e.g. Murābaḥah and Ijārah etc) on asset side. Although, these debt based modes are not against Sharīʿah, per se, however in result, these modes lead to the forms of financing similar to conventional banking system. While adopting Murābaḥah & Ijārah and other debt based financing, it was claimed by the scholars involved in the framing of the Islamic banking modes that these debt based modes are not ideal and are being adopted as necessity during the infancy, immaturity and fragility stage of the Islamic Banking sector. Gradually the system would be shifted to the ideal modes i.e. Muḍārabah and Mushārakah in due course of time. Unfortunately, the shift has been very slow and diminutive because despite passage of decades, the volume of these two ideal modes is very less. The Islamic Banking sector in Pakistan continues to thrive on the modes, which are less based on Muḍārabah and Mushārakah. In this study, endeavours have been made in general to explore the legal impediments and, in particular, those, which are preventing transition of the Islamic banking, sector of Pakistan towards the two ideal modes. While absence of self-regulating comprehensive and facilitative legal framework is the main impediment, the lack of government and regulator’s ‘will’ to advance towards Islamisation of banking system as a whole in true sense and helplessness of judiciary to legally determine the Ribā despite passage of over 40 years since incorporation about its elimination in the Constitution, 1973, are, inter alia, contributory factors giving rise to the legal impediments. The account-holders, Islamic bankers and those who avail the Islamic Financing facilities also confront such legal impediments, which impede honesty and evasion of tax payments. A self-regulating facilitative legal framework coupled with ‘strong will’ by the government and the central bank is essentially required for the transfer to the ideal modes of Islamic Banking Sector. The stakeholders in the Islamic banking sector must be ready to accept the ideal modes of Islamic banking, i.e. Muḍārabah and Mushārakah. The Resident Sharīʿah Advisers and Sharīʿah Boards’ members should lay emphasis on the management of the respective Islamic banking Institutions to formulate and introduce their products based on ideal modes. Pakistan’s judiciary, particularly, the apex court and Federal Shariat Court should endeavour to settle, once for all, the question of Ribā that is already pending re-adjudication before the FSC and appeals have also been filed before the SCP for intervention in the issue to find an early solution.