Acyl-transfer reactions have become commonplace in organic synthesis and organocatalysis of these reactions is becoming increasingly popular. 4-Dimethylaminopyridine has proven to be very useful in acylations; over the recent years chiral and more reactive analogs have received much attention. Interestingly, catalysis of acyl-transfers by diamines has also been shown to be effective. We present the synthesis of several DMAP analogs containing heteroatoms near the nucleophilic nitrogen. These analogs of DMAP vary from basic amidines, oxazolines, and amines, to alcohols, and fluoro-derivatives all of which may provide hydrogen bonding to the alcohol undergoing acyl-transfer. Since Steglich proposed the need for a base in the DMAP catalyzed acyl-transfer transition state no studies have been performed on the effect that nearby hydrogen bonding or nearby bases might have on catalytic efficiency and enantioselectivity of acylations. The variety of compounds synthesized should allow for studies into rate and selectivity enhancements in nucleophilic pyridine catalysis.

Polymer-supported reagents and catalysts have been extensively studied in the past few decades as they not only facilitate separation and isolation of products after reactions but also enable reuse of reagents/catalysts. In particular, chemistry using polymer-supported organocatalysts has the advantage of avoiding the use of sometimes toxic transition metals. Since organocatalysts are often used at high mol% loading in catalytic reactions, immobilizing organocatalysts on polymers for recycling and reusing makes chemistry using organocatalysts attractive in larger scale syntheses. Chapter II of this dissertation focuses on using variable temperature 31P NMR spectroscopy to study and compare the dynamic behavior of silver complexes prepared from soluble polymer-supported phosphines and electronically similar low molecular weight phosphine ligands. The phosphine-silver complexes supported on terminally functionalized polyisobutylene (PIB) and poly(ethylene glycol) show similar kinetic behavior compared to their low molecular weight counterparts. However, the dynamic behavior of phosphine-silver complexes supported as pendent groups on a linear polystyrene is difficult to study because of significant line-broadening on 31P NMR spectra. Chapter III of this dissertation aims at examining the recyclability and reusability of PIB-supported phosphines as organocatalysts and reagents. PIB-supported alkyldiphenyl- and aryldiphenylphosphines were prepared and used as recyclable organocatalysts in addition and allylic amination reactions. The PIB-bound phosphines were useful reagents in aza-Wittig and Mitsunobu reactions. The PIB-bound phosphine oxides formed either from adventitious oxidation or during the course of reactions can be reduce to PIB-phosphines for reuse. Chapter IV of this dissertation describes preliminary studies on soluble polymer-supported N-heterocyclic carbene (NHC) organocatalysts. PIB- and polyethylene oligomer (PE_Olig)-supported NHC adducts were synthesized and the corresponding polymer-supported NHC catalysts were generated in situ in lactide polymerization and phenyl isocyanate trimerization reactions. The PIB-bound NHC catalyst generated in situ was not recyclable in a lactide polymerization. However, PIB- and PEOlig-bound NHC precatalysts showed modest recyclability in lactide polymerization and phenyl isocyanate trimerizations.

The synthesis of compounds containing α-arylated quaternary stereogenic centres is a significant synthetic challenge. This thesis describes the development of an organocatalytic methodology for the direct construction of this motif through the Michael addition of carbon-centered pro-nucleophiles to highly reactive and unstable ortho-benzoquinones. Proof-of-principle for the base catalysed Michael addition to ortho-quinones was established with stable 1,2-naphthoquinone (Chapter 2), however typical orthobenzoquinones were found to be too unstable to use in this process. Accordingly an oxidative coupling strategy was developed for in-situ generation of the obenzoquinone electrophile (Chapter 3.1). The base catalysed Michael addition followed by aromatisation allows for the direct construction of arylated quaternary stereocentres. An asymmetric variant was also developed by replacing the base catalyst with a cinchona alkaloid derived organocatalyst, up to 82% ee was achieved (Chapter 3.2).The methodology was then applied to the racemic total synthesis of the amaryllidaceae alkaloids powelline and buphanidrine (Chapter 4). The oxidative coupling methodology allowed rapid construction of the sterically congested arylated quaternary stereocentre in the key step of the syntheses, which were then completed in 13 and 14 steps respectively in 6% overall yield. Employing a quinidine derived organocatalyst in the oxidative coupling step gave the arylated product in 57% yield (3 steps) and 70% ee (Chapter 5). However, the enantioselective total synthesis was thwarted by racemisation during the Dieckmann-type cyclisation for the formation of enol ether 212 and an alternative synthetic strategy will berequired to synthesise the enantiopure alkaloid.

<p> The catalytic asymmetric transformation of carbonyl compounds via iminium and enamine intermediates using chiral amines as organocatalyst has grown remarkably over last decade. Various "metal-free" reactions including aldol, Mannich, Michael, alkylation and Knoevenagel types have now been reported efficiently using simple amino acids as the sole organocatalysts. Amongst these, proline has proven to be particularly useful as a general catalyst in such catalytic asymmetric syntheses due to its unique properties. Nonetheless, proline suffers inherent fundamental disadvantages as an organocatalyst in terms of its solubility in organic media, limiting reactions to polar aprotic solvents such as DMF or DMSO. We have been interested in the synthesis of derivatives of proline incorporating functional groups that would render the chiral secondary amine fully soluble in organic solvents such as THF or dichloromethane and others that could be employed in aqueous media. The synthesis of these catalysts and their application towards the asymmetric synthesis will be presented.</p> <p> The thesis also describes isolation and identification of natural products and synthesis of their semi-stabilised derivatives. Sakuranetin and dihydrowagonine were isolated from Prunus avium plant parts, menisadurilide was isolated from Dicentra spectabilis extracts while narciclasine was isolated from Narcissus pseudonarcissus plant parts. Semi-synthetic derivative, trans-dihydronarciclasine was prepared from natural product narciclasine. Both the derivatives were subjected to antifungal and human cytochrome inhibition activity and their correlation is explained. The Amaryllidaceae family alkaloids and their semi-synthetic derivatives were subjected to biological testing and an important structural property is correlated to their activities.</p> / Thesis / Master of Science (MSc)

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18092号 / 理博第3970号 / 新制||理||1572(附属図書館) / 30950 / 京都大学大学院理学研究科化学専攻 / (主査)教授 丸岡 啓二, 教授 大須賀 篤弘, 教授 時任 宣博 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18814号 / 理博第4072号 / 新制||理||1586(附属図書館) / 31765 / 京都大学大学院理学研究科化学専攻 / (主査)教授 丸岡 啓二, 教授 大須賀 篤弘, 教授 時任 宣博 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(薬科学) / 甲第19660号 / 薬科博第48号 / 新制||薬科||6(附属図書館) / 32696 / 京都大学大学院薬学研究科薬科学専攻 / (主査)教授 川端 猛夫, 教授 高須 清誠, 教授 竹本 佳司 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20388号 / 工博第4325号 / 新制||工||1670(附属図書館) / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 松原 誠二郎, 教授 吉田 潤一, 教授 中尾 佳亮 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20947号 / 理博第4399号 / 新制||理||1632(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 丸岡 啓二, 教授 依光 英樹, 教授 大須賀 篤弘 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

学位プログラム名: 京都大学大学院思修館 / 京都大学 / 0048 / 新制・課程博士 / 博士(総合学術) / 甲第21231号 / 総総博第3号 / 新制||総総||1(附属図書館) / 京都大学大学院総合生存学館総合生存学専攻 / (主査)教授 竹本 佳司, 特定教授 大嶌 幸一郎, 教授 大野 浩章 / 学位規則第4条第1項該当 / Doctor of Philosophy / Kyoto University / DFAM