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ABSTRACT DOĞUTAN, DILEK. New Strategies for the Synthesis Of ABSTRACT DOĞUTAN, DILEK. New Strategies for the Synthesis of Substituted Magnesium Porphyrins. (Under the direction of Professor Jonathan S. Lindsey). Porphyrins are valuable compounds for studies in biomimetic and materials chemistry. Efficient routes for the synthesis of porphyrins bearing distinct types and patterns of substituents are essential for such studies and for diverse applications. A new set of conditions has been developed for the synthesis of a broad class of porphyrins. The conditions entail a metal salt (MgBr2; 3 mol equiv versus the reactant) and a non-coordinating base (DBU; 10 mol equiv versus the reactant) in a non-coordinating solvent (toluene) with heating (conventional or microwave irradiation) in the presence of air. The reaction of 1-formyldipyrromethane under such basic, Mg-mediated conditions afforded Mg(II)porphine in 30-40% yield. The advantages of the new method include simplicity, high concentration, chromatography-free purification, gram-scale synthesis, and avoidance of the poorly soluble free base porphine. Mg(II)porphine exhibits good solubility in common organic solvents and is a valuable core scaffold for derivatization (Chapter 1). New methodology is described for the synthesis of porphyrins bearing four (A4, cis-A2B2, cis-ABC2, trans-A2B2) or fewer (A, cis-AB, cis-A2, trans-A2) meso-substituents. The rational synthesis of trans-A2B2- or trans-A2-porphyrins was achieved via condensation of two identical 1-acyldipyrromethanes. The statistical synthesis of various meso-substituted porphyrins was achieved via condensation of two non-identical 1-acyldipyrromethanes. Both routes possess attractive features including (1) no scrambling, (2) good yield (up to 60%) at high concentration (100 mM) for the macrocycle-forming step, (3) reasonable scope (aryl, heteroaryl, alkyl, or no substituent), (4) short reaction time (~2 h) via microwave irradiation, (5) magnesium porphyrins as the products, which easily undergo demetalation, and (6) facile chromatographic purification. A key advantage of the statistical route is to obtain a cis-substituted porphyrin without the corresponding trans isomer. In total, 26 1-acyldipyrromethanes and 26 target porphyrins have been prepared, including many with two different pyridyl substituents. One set of amphipathic porphyrins includes cis-A2B2- or cis-A2BC-porphyrins wherein A = pentyl and B/C = pyridyl (o- , m-, p-). Taken together, the rational and statistical routes enable facile conversion of readily available 1-acyldipyrromethanes to diverse porphyrins bearing 1-4 meso substituents for which access is limited via other methods (Chapter 2). A new route has been developed for preparing porphyrins bearing up to four different meso-substituents (ABCD-porphyrins). The new strategy relies on two key reactions. One key reaction entails a directed synthesis of a 1-protected 19-acylbilane by acid-catalyzed condensation at high concentration (0.5 M) of a 1-acyldipyrromethane and a 9-protected dipyrromethane-1-carbinol. Three protecting groups were examined, including thiocyanato, ethylthio, and bromo, of which bromo proved most effective. The bilanes were obtained in 72 to 80% yield, fully characterized, and examined by 15N NMR spectroscopy. The second key reaction entails a one-flask transformation of the 1-protected 19-acylbilane under the basic Mg- mediated porphyrin-forming conditions. The target magnesium porphyrin is obtained in 65% yield (Chapter 3). The new route to bilanes and porphyrins bearing four distinct meso substituents has been studied to elucidate the scope and gain entry to previously inaccessible compounds. In total, 19 new porphyrins having alkyl, aryl, heterocylic or no substituent have been synthesized (Chapter 4). The bilanes were obtained in 35-87% yield, and the target porphyrins in up to 60% yield. Further study of the scope focused on bilanes and porphyrins bearing three heterocyclic substituents (o-, m-, p-pyridyl) or four alkyl groups (ethyl, propyl, butyl, pentyl), in which case microwave irradiation was used for the porphyrin-forming step. Altogether, 17 bilanes and 19 porphyrins were prepared and characterized. In summary, the basic Mg-mediated conditions provide facile access to novel substituted porphyrins which should facilitate a wide variety of studies. New Strategies for the Synthesis of Substituted Magnesium Porphyrins by Dilek Doğutan A dissertation submitted to the Graduate Faculty of North Carolina State University In partial fulfillment of the Requirements for the degree of Doctor of Philosopy Chemistry Raleigh, North Carolina June 2008 APPROVED BY: _______________________________ ______________________________ Jonathan S. Lindsey Daniel L. Comins Committee Chair ________________________________ ________________________________ David A. Shultz Reza A. Ghiladi DEDICATION I would like to dedicate this work in the loving memory of my father Abdullah Atila Doğutan. Although he is no longer with me physically, he will be forever with me in spirit. Thank you very much for everything that you have done for me. I am deeply sorry for not being with you when you needed me the most. I will always work very hard and make you proud of me. I love you and miss you so very much. Doktora tezimi sevgili babam Abdullah Atila Doğutan’a ithaf etmek istiyorum. Canim babaciğim bizler ile fiziksel olarak beraber değilsen bile, senin sevgin ve güzel anilarimiz herzaman kalbimde yaşayacak. Bizleri okutmak için annemle beraber yaptiğiniz tüm özveriler için sana ve anneme minettarim. Seni rahatsizliğin süresince ziyaret edemediğim, son gününde yaninda olamadiğim için çok üzgünüm. Şimdiye kadar oldugu gibi bundan sonrada bize öğrettiğin değerlerle yaşayarak benimle gurur duyman için elimden geleni yapacağim. Tekrar görüşünceye kadar seni çok seviyor ve özlüyorum benim canim babaciğim. ii BIOGRAPHY The author, Dilek Doğutan, was born in Istanbul, Turkey. After graduating from Erenköy Kiz Lisesi (High School) in Istanbul, Turkey, Dilek prepared for the competitive examination regulating entry into Middle East Technical University (METU) in Ankara, Turkey. Following the examination, she joined the Department of Chemistry at METU. After graduating from METU, Dilek started working in a pharmaceutical company, Ilsan-Iltas & Hexal, Inc., as a research scientist and worked in both Istanbul, Turkey and Munich, Germany. She applied for graduate schools in the USA and joined the North Carolina State University Department of Chemistry. She began her dissertation under the supervision of Dr. Jonathan S. Lindsey. Dilek was recognized with the Outstanding Graduate Research Accomplishment Award in chemistry in 2005 and 2007 by North Carolina State University Department of Chemistry. Dilek graduated from North Carolina State University in 2008. Upon completion of her Ph.D., she began a postdoctoral position at the Massachusetts Institute of Technology under the direction of Dr. Daniel G. Nocera. iii ACKNOWLEDGMENTS I would like to express my deepest gratitude to my research advisor Dr. Jonathan S. Lindsey for his mentorship, advice, and support. Thank you very much for allowing me to perform research in your laboratory and also giving me the opportunity to work on very challenging projects. I would also like to thank my committee members Dr. Daniel L. Comins, Dr. David A. Shultz, Dr. Reza A. Ghiladi, Dr. Christian C. Melander, Dr. Melissa A. Pasquinelli, and Dr. Sharon R. Lubkin for reviewing my work. I would like to extend my appreciation to the faculty and staff of the North Carolina State University Department of Chemistry for all the support that they provided me. I thank the present and past members of the Lindsey research group. I am grateful to Dr. Marcin Ptaszek, Dr. Christian Ruzié, Dr. Han-Je Kim, Dr. W. Justin Youngblood, Dr. Jayeeta Bhaumik, and Dr. Masahiko Taniguchi for their friendship, support, and encouragement. I also would like to acknowledge Ann Norcross for her kind assistance over the years. I would like to thank my family for their continous support. I would not be where I am today without you. I would like to thank my father Abdullah Atila Doğutan and my mother Ayşe Doğutan for all the sacrifices that they have made for me. It was your unconditional love and support which has kept me going all these years. I would like to acknowledge my sisters Necla Doğutan, Meryem Doğutan, Arife Doğutan, and Associate Professor Melek Doğutan Yenidünya for helping me during my education. I truly appreciate everything that you have done for me. I especially thank Associate Professor Melek Doğutan Yenidünya for being a true inspiration to me during my education. I would like to express my special thanks to my brother Mehmet Ali Atalay Doğutan. Finally, I would like to thank my loving husband Halil Kiper. I cannot express iv enough how much I appreciate your continous love and support. I know that you are always there for me and share a big part in all my accomplishments. I am looking forward to having a wonderful life with you and I love you very much. v TABLE OF CONTENTS LIST OF TABLES ....................................................................................................................... xiii LIST OF FIGURES ..................................................................................................................... xiv LIST OF CHARTS ........................................................................................................................xv LIST OF SCHEMES...................................................................................................................
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