Synthesis and Evaluation of Functionalized Imidazole and Triazoles as Novel Anti-fungal Agents A THESIS PRESENTED TO THE FACULTY OF THE UNIVERSITY OF MINNESOTA BY GRADY L. NELSON IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE DR. VENKATRAM R. MEREDDY SEPTEMBER 2014 © Grady L. Nelson. September 2014 ACKNOWLEDGEMENTS I would like to express my greatest gratitude to Dr. Venkatram Mereddy who has helped and supported me through my graduate career. I am grateful to my teacher for his continuous support, valuable advice, and his colossal amount of patience. I would also like to thank the members of my committee Dr. Erin Sheets and Dr. Steven Berry for their valuable time and help. Department of Chemistry and Biochemistry for its financial support for the past two years. I would also like to thank the faculty in the Department of Chemistry and Biochemistry for the knowledge and skills they have taught me. At last but not least I would like to thank my family Catherine, Gary and Jessica Nelson for their continued support and interest in my research and schooling. i ABSTRACT GRADY L. NELSON, Synthesis and Evaluation of Functionalized Imidazoles as Novel Anti-Fungal Agents, Master of Science (Department of Chemistry and Biochemistry), University of Minnesota. Fungal species are highly prevalent in our environment. Some are relatively harmless but there are others that are pathogenic. A problem arises when dermatophytes enter into the blood system. Commonly associated with immunocompromised patients, fungemia is when a fungal species enters the blood stream. Currently there are many treatments but there is a growing fear of resistance to these drugs and a need for novel therapeutics. The Baylis-Hillman reaction is a flexible template in which an aldehyde and various acrylates form a highly functionalized Baylis-Hillman derivative. In this paper, a small library of Baylis-Hillman reaction-derived imidazole and triazoles are synthesized and characterized. Furthermore, their anti-fungal activities are evaluated against Candida albicans and Cryptococcus neoformans. It was found that some of the derivatives showed moderate to good activity against Candida albicans (MIC 213-46.5 µg/ml) and Cryptococcus neoformans (MIC 5.50-1.68 µg/ml). ii TABLE OF CONTENTS I. ACKNOWLEDGEMENTS i II. ABSTRACT ii III. TABLE OF CONTENTS iii IV. LIST OF SCHEMES iv V. LIST OF FIGURES vi VI. LIST OF TABLES vi VII. LIST OF ABBREVIATIONS vii VIII. CHAPTER 1: INTRODUCTION 1 IX. CHAPTER 2: RESULTS AND DISCUSSION 26 X. CHAPTER 3: SPECTRAL CHARACTERIZATION 49 XI. REFERENCES 71 XI. APPENDIX A 75 iii LIST OF SCHEMES Scheme Title of the scheme Pg.No. Scheme 1.1 Multicomponent coupling for 1,2,4,5 – tetrasubstituted 3 imidazoles Scheme 1.2 Synthesis of naphthalimido imidazoles and triazoles 4 Scheme 1.3 Formation of 1-(3,5-diaryl-4,5-dihydro-1H-pyrazol-4- 5 yl)-1H-imidazole Scheme 1.4 Synthesis of the benzoxazinyl imidazole hybrids 6 Scheme 1.5 Synthesis of berberbine-imidazole hybrids 7 Scheme 1.6 Synthesis of novel 2-acetylnaphthalene derivatives 9 Scheme 1.7 Synthesis of a library of di-substituted imidazole based 10 alcohols Scheme 1.8 Synthesis of triazole clubbed benzothiazoles 11 Scheme 1.9 Synthesis of a series of Schiff base triazoles 14 Scheme 1.10 Synthesis of fluconazole based derivatives 16 Scheme 1.11 Synthesis of coumarin coupled triazole hybrids 18 Scheme 1.12 Hybrid derivatives of fluconazole and clinafloxacin 12 Scheme 1.13 Synthesis of fluconazole based derivatives 18 Scheme 1.14 Synthesis of novel 1,2,4-triazone based triazoles 19 iv Scheme 1.15 Synthesis of novel imidazole substituted phenyl 21 pyrrolylmethanones Scheme 1.16 Synthesis of a series of novel piperazine coupled 22 ketoconazole analogues Scheme 1.17 Synthesis of carbazole based imidazole and their 23 chloride salts Scheme 1.18 Synthesis of 2-phenyl-alkylbenzofurans 25 Scheme 2.1 Baylis-Hillman Reaction 27 Scheme 2.2 Nucleophilic Substitution of Baylis Hillman 33 derivatives Scheme 2.3 Baylis-Hillman Template 28 Scheme 2.4 Synthesis of imidazole and triazole derivatives 29 Scheme 2.5 Synthesis of electron donating group substituted 2- 30 (imidazolylmethyl) and 2-(triazolylmethyl) cinnamates Scheme 2.6 Synthesis of electron withdrawing group substituted 34 cinnamonitriles Scheme 2.7 Synthesis of β-Imidazolyl Styryl Methyl Ketone 35 v LIST OF FIGURES Figure 1.1 Commonly used fungal drugs 2 Figure 2.1 Baylis-Hillman template 28 Figure 2.2 Electron donating group substituted 2-(imidazolylmethyl) and 2- 31 (triazolylmethyl) cinnamates Figure 2.3 Electron withdrawing group substituted 2-(imidazolylmethyl) 32 cinnamates Figure 2.4 Electron withdrawing group substituted 2-(triazolylmethyl) 33 cinnamates Figure 2.5 Electron withdrawing group substituted 2-(imidazolylmethyl) 34 and 2-(triazolylmethyl) cinnamonitriles Figure 2.6 Electron donating group substituted 2-(imidazolylmethyl) styryl 35 methyl ketones Figure 2.7 2-(Imidazolylmethyl)/ 2-(aminomethyl) cinnamates 36 Figure 2.8 Inference 47 Figure 2.9 Proposed further studies 48 LIST OF TABLES Table 1 Zone of inhibition of imidazoles and triazoles 37 Table 2 Minimum inhibitory concentration of imidazoles and triazoles 43 against Cryptococcus neoformans (ATCC 32045) Table 3 MIC of imdazoles and Triazoles against Candida albicans 44 (ATCC 90028) vi LIST OF ABBREVIATIONS MIC Minimum inhibitor concentration NH4OAc Ammonium Acetate Cu(NO3)2 Copper (II) Nitrate CH3CN Acetonitrile K2CO3 Potassium Nitrate NaH- Sodium hydride THF- Tetrahydrofuran DMF- N, N – Dimethylformamide tBuOK Potassium tert-butoxide Ts p-toluenesulfonate Ms methanesulfinate PBr3 Phosphorous Tribromide EtOH Ethanol DCC N,N’-Dicyclohexylcarbodiimide vii DMAP 4-Dimethylaminopyridine NaBH4- Sodium borohydrate AcOH Acetic Acid NH2NH2 Hydrazine Hydrate POCl3 Phosphoryl chloride CS2 Carbon Disulfide AlCl3 Aluminum Chloride NaHCO3 Sodium Carbonate NaN3 Sodium azide CuSO4 Copper (II) sulfate CHCl3 Chloroform CH2Cl2 (DCM) Methylene chloride (Dichloromethane) Et3N Triethylamine LiAlH4 Lithium aluminum hydride DMA- Dimethylacetamide DMSO- Dimethyl sulfoxide MsCl Methanesulfonyl chloride DABCO 1,4-diazabicyclo[2.2.2]octane viii Ac2O Acetic anhydride H2SO4 Sulfuric acid Nu Nucleophile EWG Electron withdrawing group Py Pyridine AcCl Acetyl chloride ix Chapter 1: Introduction Fungal species are prevalent and many of them are harmless or even good for the environment. However, there are specific strains that are pathogenic. These strains usually are contagious and easily contracted when present. Dermatophytes describes fungal species that cause infections of the skin, hair, and nails and affect at least 10% of the population. Their ability to survive in these conditions comes from the ability to metabolize keratinized material.1 A common infection of the fungal variety is candidiasis. This classification of infection is usually caused by Candida albicans, which is one of the most opportunistic species of fungus in immuno- compromised patients. This type of infection can be divided into two types: superficial and systemic.1 Superficial fungal infections are commonly referred to as thrush, whether oral or vaginal, and it is distinguished by an overgrowth of a fungal species. Vaginal candidias is commonly referred to as yeast infection and affects seventy five percent of women.2 Systemic fungal infections are internal fungal infections that spread through the body, and are usually life threatening. In a hospital setting candidias is the prevalent systemic fungal infection and is ranked fourth in hospital acquired blood stream infections, and is called candidemia.3 Although candidias is the most prevalent, it is part of a much larger problem known as fungemia. Fungemia is a normal fungal infection invading the blood stream, and it is one of many health care associated infections known as mycoses. Systemic mycoses due to opportunist pathogens is most commonly attributed to fungal species, in particular Candida, Aspergillus, and Cryptococcus.4 Candida is the most prevalent form of mycoses. It has been found that sepsis caused by fungemia has increased by 207% between 1979 and 2000,5 and the list of fungemia causing species are increasing 1 every year.3-6 Mycosis is commonly associated with immuno-compromised patients although they are not the only ones at risk. One of the most common ways an immuno- competent person can contract a systemic fungal infection is through intensive care centers, specifically through catheters. A recent report from a cancer center stated that most infections were catheter-related fungemias.4-7 Over the years there have been many advances in the treatment of these fungal infections in the form of various imidazole and triazole drugs. Some of the clinically used drugs are shown below (Figure 1). 2 Figure 1: Commonly used fungal drugs However, many of these fungal species have become resistant to these common drugs over the years.7 Resistance has spurred new interest in novel structures, leading to an increased rush towards the development of new generation anti-fungal agents. The following paragraphs outline some of the recent molecules that have been synthesized for antifungal activity that showed some potency, and influenced the design of our library. Sivakumar et al. reported a simple methodology involving multicomponent coupling of diketones with aldehydes and amines for the synthesis of functionalized 8 1,2,4,5-tetrasubstituted imidazoles 4 (Scheme 1.1). Zeolite supported Cu(NO3)2 was used as a catalyst in this reaction. Specifically, this