<strong>Introduction</strong> The introduction describes the importance of arylamine compounds to society and provides a brief overview of the methods available for their synthesis. The application of metathesis catalysis to the de novo synthesis of heteroaromatic compounds is also described. <strong>Results and discussion</strong> The first section describes efforts towards the de novo synthesis of arylamines using a cross metathesis/oxidation protocol to form a 1,5-unsaturated dicarbonyl followed by an amine mediated cyclisation. The scope with respect to the 1,5-unsaturated dicarbonyl and amine is covered as well as the utility of some of the products. The section concludes with a modification of the Bohlmann Rahtz pyridine synthesis to furnish arylamines. The next section describes the applications of our methodology to the synthesis of naphthylamines, specifically using the palladium catalysed &alpha;-arylation reaction. A discussion of the α-arylation reaction is included as well as our efforts to explore the scope of the reaction. The third section follows our efforts to apply this methodologyy to the synthesis of five benzo[c]phenanthridine alkaloids including the first reported synthesis of maclekarpine B and C. The final section concludes with a discussion of our efforts towards the de novo synthesis of furans bearing a benzylic stereocentre.

This thesis describes the studies towards the synthesis of β-amino acids found in the microsclerodermins, a family of complex macrocyclic hexapeptides. These β-amino acids have four or five contiguous stereocentres and an aliphatic side-chain. The synthetic route utilised an aminohydroxylation reaction to install the most challenging moiety in the structure - the 1,2- amino alcohol. The work aimed to construct the core structure (five contiguous stereocentres) of the β-amino acids and install the side-chain later to enable the synthesis of multiple members (A, B, F, G, H and I) of the microsclerodermin family. The synthesis started with Roche ester, which contained the first methyl stereocentre. It was converted to the diene precursor in four high yielding steps. The next two stereocentres were installed via a Sharpless asymmetric dihydroxylation. With the appropriate protecting groups in place, the remaining two stereocentres were to be installed via a Sharpless asymmetric aminohydroxylation. Various reported reagents and conditions were used to effect the transformation, but the attempts were unsuccessful. This forced us to alter our synthetic plans, and the revised synthetic route involved the use of the tethered aminohydroxylation (TA) reaction developed by the Donohoe group. After the development of an efficient protocol to prepare the TA-precursor, the alkene, with three stereocentres already in place, was successfully converted to the desired stereopentad via the TA-reaction (10 steps, 11% overall yield). With the stereopentad in hand, installation of the side-chain of the β-amino acids through an alkenyl or alkyl linkage was investigated. For alkenyl-linked side-chains, the appropriate aldehyde was synthesised, but attempts to effect the transformation via a Horner-Wadsworth- Emmons reaction or a Witting reaction failed. With lessons learnt from those, we then focused our efforts on installing an alkyl-linked side-chain. In this case, we were able to install a side- chain via a copper-mediated displacement reaction, which gave us a protected form of the precursor of the β-amino acid of microsclerodermin B. Finally, various efforts to study the reactivity of the stereopentad and the investigations into finding the most effective set of protecting groups have been used to propose a synthetic route for the incorporation of the β- amino acid into the macrocycle.

Thesis advisor: Amir H. Hoveyda / Chapter 1. The first examples of highly Z- and enantioselective ring-opening/cross-metathesis reactions are disclosed. Transformations involve meso cyclic olefin substrate and styrenes or enol ethers as olefin cross partners. A stereogenic-at-Mo monoaryloxide monopyrrolide (MAP) complex, prepared and used in situ, is discovered for the efficient formation of Z olefins. Such complex, bearing a relatively smaller adamantylimido and a larger chiral aryloxide ligand, leads to kinetic Z-selectivity due to the size differential. In most cases, the resulting disubstituted Z olefins are formed with excellent stereoselectivity (>95% Z). Chapter 2. The protocols for efficient Z-selective formation of macrocyclic disubstituted alkenes through catalytic ring-closing metathesis (RCM) is described. Stereoselective cyclizations are performed with either Mo- or W-based monoaryloxide monopyrrolide (MAP) complex at 22 oC. Synthetic utility of such broadly applicable transformation is demonstrated by synthesis of several macrocyclic natural products: relatively simpler molecules such as epilachnene (91% Z) and ambrettolide (91% Z), as well as advanced precursors to epothilones C and A (97% Z) and nakadomarin A (94% Z). Several principles of catalytic stereoselective olefin metathesis reactions are summarized based on the studies: 1) Mo-based catalysts are capable of delivering high activity but can be more prone to post-RCM isomerization. 2) W-based catalysts, though furnish lower activity, are less likely to cause the loss of kinetic Z selectivity by isomerization. 3) Reaction time is critical for retaining the stereoselectivity gained from kinetic, which not only applicable with MAP complexes but potentially with other complexes as well. 4) By using W-based catalyst, polycyclic alkenes can be accessed with sequential RCM reactions, without significant erosion of the existing Z olefins in the molecule. Chapter 3. An enantioselective total synthesis of anti-proliferative agent (+)-neopeltolide is presented. The total synthesis is accomplished in 11 steps for the longest linear sequence and 28 steps in total, including 8 catalytic reactions. Particularly, several Mo- or Ru-catalyzed stereoselective olefin metathesis reactions as well as N-hetereocyclic carbene (NHC)-catalyzed enantioselective boron conjugate addition to an acyclic enoate have proven to be effective for convergent construction of the molecule. The most important novelty of the study incorporates the explorations of feasibility of Z-selective cross-metathesis reactions to solve the challenge of installing two Z olefins with excellent selectivity. / Thesis (PhD) — Boston College, 2014. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

In 1982, routine screening of the Pseudopterogorgia elizabethae stirred the scientific community by showing the presence of cytotoxic metabolites with antimicrobial activity. Since this discovery a vast amount of research has been conducted in synthesising metabolites of the soft coral. Herein we report the developments towards the synthesis of two metabolites (+)-Erogorgiaene and (+)-Elisabethadione utilising three key reactions in setting up the molecules three chiral centres. The use of asymmetric allylation, oxy-Cope rearrangement and cationic cyclisation was utilised to set up the desired stereocentres from a starting cinnamyl aldehyde. Natural elisabethadione was synthesised in a racemic form as a 2:1 mixture of diastereoisomers at the C-13 stereocentre.

Dietary fish oil supplementation has long been shown to have significant health benefits, largely stemming from the anti-inflammatory activity of the ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) present in fish oils. The anti-inflammatory properties of these fatty acids has been linked to beneficial health effects, such as protecting the heart, in individuals consuming diets rich in fish, or supplemented with fish oils. These effects are highly notable in the Māori people native to coastal regions of New Zealand; the significantly lower rates of heart problems compared to the inland populous has been attributed to the consumption of the green lipped mussel Perna Canaliculus. Commercially available health supplements based on the New Zealand green lipped mussel include a freeze-dried powder and a lipid extract (Lyprinol®), the latter of which has shown anti-inflammatory properties comparable to classical non-steroidal anti-inflammatory drugs (NSAIDs) such as Naproxen. GCMS analysis of Lyprinol by Murphy et al. showed the presence of a class of ω-4 and ω-6 PUFAs bearing a highly electron rich tri- or tetra-alkyl furan ring, which were designated furan fatty acids (F-acids). Due to their instability, isolation of F-acids from natural sources cannot be carried out and a general synthetic route toward this class of natural products was required. To accomplish this, the biosynthesis of F-acids was mimicked by utilising an oxidation of 1,3-dienes, followed by a dehydration/aromatisation to generate the heterocyclic furan ring. Singlet oxygen was chosen as the means of oxidising the conjugated dienes giving endoperoxides. To mimic the biological aromatisation of the peroxide intermediates the Appel reagent was chosen and, in a novel application of the reagent, was exploited as a mild, metal free method of dehydrating the cyclic peroxides to their corresponding furans. The biomimetic furan synthesis was applied toward a selection of 1,3-diene substrates bearing a range of pre-installed functionalities and substitution patterns including alkyl, aryl, alkenes, cyclopropyl rings, silyl ethers, and esters, alongside being applied to the total synthesis of the furan fatty acid F5. A brief exploration of the possibility of performing the aromatisation reaction under catalytic conditions was carried out, to determine whether endoperoxides could be converted to furans without needing a stoichiometric quantity of Appel reagent, by harnessing a catalytic quantity of triphenylphosphine oxide and regenerating the active P(V) species via reaction with oxalyl chloride. Furthermore, an optimisation study was carried out using a simple design of experiments procedure to ascertain the ideal conditions for carrying out the Appel-type dehydration of endoperoxides. Finally, the scope of the reaction sequence was expanded to be performed in a continuous flow reactor, with telescoping of the singlet oxygen diene oxidation and Appel-type aromatisation to increase oxidation yields and to omit the requirement for isolation of peroxide intermediates, and was applied to the synthesis of a selection of 2,5-diaryl furan motifs.

Natural product synthesis has been a most exciting and challenging branch of organic chemistry in view of its creative power and unlimited scope. Natural product synthesis witnessed an unprecedented growth and innovative developments, especially during the later half of the 20th century. This can be attributed to a number of factors, one of which has been the isolation and characterization of growing number of compounds from natural sources through availability of newer techniques of isolation and purification and advances in the incisive tools (eg. 2D NMR, X-ray, HRMS) of structure determination. Many natural products, though scarce from natural resources, possess wide ranging biological activity and need to be accessed through synthesis for clinical development and evaluation, particularly of analogs. This has been one of the main stimuli in recent years for undertaking the synthesis of natural products. Among the diverse architecture created by Nature, terpenoids are the most variegated in terms of the presence of a bewildering array of carbocyclic frameworks with unusual assemblage of rings and functionalities. This phenomenal structural diversity of terpenoids makes them challenging targets for total synthesis and for the articulation of new synthetic strategies for carbocyclic ring construction. One of the major concerns in organic chemistry, particularly of relevance in synthesis is the control of diastereoselectivity in nucleophilic and electrophilic additions to trigonal carbon atoms as this is the fundamental step in stereogenesis. Several approaches have been devised to achieve diastereoselection and to understand the interplay of underlying stereoelectronic factors. In this context, introduction of newer probe systems and search for incisive interpretations are continuously enriching the area. The present thesis addresses both the above mentioned themes of contemporary interest in organic chemistry and is presented in two main parts. Part-1: A Total Synthesis of Novel Sesquiterpenoid Natural Product (±)-Merrilactone A. Part-2: A Study of -Face Selectivity in Additions to Trigonal Carbon Centers in Iso-steric Environments. The Part-1 describes our travails towards a stereoselective construction of the complex framework present in the biologically potent and structurally novel sesquiterpene natural product Merrilactone A culminating in its total synthesis. The Part-2 narrates the results of -face selectivity in addition reactions to two novel systems, exo-5-subtituted bicyclo[2.1.1]hexan-2-ones, 5-exo-substituted 2-methylene-bicyclo[2.1.1]hexane and 1-substitued tricyclo[2.1.0.02,5]pentan-3-ones, employing various nucleophiles and electrophiles

The health benefits of fish oil supplementations have been proven to be effective by several studies which are discussed in this thesis. It was found that these compounds had potent anti-inflammatory properties and since then has prompted much research into the use of these compounds as potential treatments for chronic inflammation based diseases, where the overuse of current anti-inflammatory drugs cause many problems with undesired side-effects. The aim of this research is to study the bioactivity of resolvin E1 and various analogues, and to determine a novel route towards resolvin E1 natural product so that bioactivity tests may be conducted in comparison of synthetically produced resolvin E1 and naturally extracted resolvin E1. The initial aim of this research was to develop a range of analogues of a fragment of Resolvin E1. This was so that a series of compounds could be produced with various R groups to identify any structure-activity relationships for this part of the natural product. There is one stereocentre in this fragment of resolvin E1 and it was decided that a racemic version of these compounds would be tested for bioactivity, and if any of the compounds had significant anti-inflammatory properties then the R and S versions could be separated, allowing for the testing of both enantiomers to determine which gave the most potent anti-inflammatory response. This led to the creation of several novel fragments and their biological testing. The secondary aim of the project was to complete the total synthesis of the resolvin E1 natural product. We devised a novel route towards resolvin E1 which used MIDA boronate protecting group to introduce a fixed trans double bond which was useful in a compound with multiple alkene systems. Resolvin E1 also contains three stereocentres, the synthesis from the fragment work was recycled to begin the synthesis, and made use of 1,2:5,6-di-O-isopropylidene-D-mannitol and Noyori s catalyst to setup the stereocentres. The use of new MIDA-boronate moieties were also explored in order to develop a new, efficient synthesis toward resolvin E1.

This thesis describes the development of a synthetic route towards daphlongeranine B, an alkaloid isolated from the fruits of Daphniphyllum longeracemosum, by utilising an intramolecular Michael addition to form its unique tricyclic core. <strong>Chapter 1</strong> gives a general introduction to the family of Daphniphyllum alkaloids together with some recent examples, from the literature, illustrating some synthetic attempts towards structurally similar alkaloids. This chapter also features our retrosynthetic analysis of daphlongeranine B. <strong>Chapter 2</strong> details the synthesis of the model spirocyclic enone 72 which was the vital building block needed to investigate the key intramolecular Michael addition. This key reaction was then successfully validated and access to the unique tricyclic core 64 of daphlongeranine B was made possible. <strong>Chapter 3</strong> expands the scope of the key intramolecular Michael addition step. This chapter first describes a synthetic route to the Î2-substituted spirocyclic enone 112 and subsequently validates the key intramolecular Michael addition step to give the tricyclic core 138 of daphlongeranine B. <strong>Chapter 4</strong> details a synthetic route towards the spirocyclic fragment 141 by utilising a Baker's yeast reduction and a tandem addition/cyclisation reaction.

An efficient approach to the hydrobenzofuro[3,2-b]chromenone core of sanggenon-type natural products has been developed. The key transformation involves a protecting group-free double rearrangement of a bis-allyloxyflavone ether substrate. A sequence involving asymmetric 3-allyl rearrangement followed by aromatic Claisen rearrangement has been established for the asymmetric synthesis of the hydrobenzofuro[3,2-b]chromenone core structure. This methodology has been successfully applied to asymmetric syntheses of both sanggenol F and sanggenon A. Efficient chiral, racemic syntheses for sanggenons C and O have been achieved. The key transformation entails a biomimetic Diels-Alder cycloaddition between a flavonoid diene and a 2'-hydroxychalcone. The flavonoid diene was produced from a protected flavonoid chromene via isomerization. Metal-catalyzed alkynyl Claisen (Saucy-Marbet) rearrangements of 3-alkynyl flavone ethers have been evaluated, and a 1,2-acyl migration cascade which afforded novel furanyl benzofuranone scaffolds was discovered. Mechanistic studies have revealed that the rearrangement is likely initiated by 5-endo enyne cyclization to a platinum-containing spiro-oxocarbenium intermediate, which may be intercepted by methanol to produce a spirodihydrofuran or further rearranged to afford allenyl chromanediones and benzofuranones at higher reaction temperature. Lewis acid-catalyzed [1,3]-rearrangements of 3-aryl substituted flavone ethers have also been developed.

No description available.