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Thesis advisor: Marc L. Snapper / Thesis (PhD) — Boston College, 2008. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

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<p> Reaction of tetraphenylcyclobutadienepalladium halides, [(Ph4C4)PdX2]2, with [(C5H5)M(CO)3]2 (M=Mo or W) gave complexes of the type (Ph4C4)(C5H5)M(CO)X (M=Mo, X=Cl, Br or M=W, X=Br). Conversely, reaction of [(R4C4)PdBr2]2 (R=C6H5, p-CH3C6H4) with [(C5H5)Fe(CO)2]2 or (C5H5)Fe(Co)2Br led not to the expected transfer of the cyclobutadiene ring group onto iron, but to complexes of the type [(R4C4)M(C5H5)]+ FeBr4- (M=Pd or Ni). These were converted into the diamagnetic bromides. [(R4C4)M(C5H5)]+ Br- which, on treatment with sodium methoxide, gave the cyclobutenyl complexes (R4C4OMe)M(C5H5) of palladium and nickel.</p> <p> The complexes (R4C4)Co(Co)2X (R=C6H5, p-CH3C6H4, X=halogen) have been prepared by ligand-transfer reactions from [(R4C4)PdX2]2. The reactions of (R4C4)Co(CO)2X show considerable similarity to those of (C5H5)Fe(CO)2X, and evidence for a very strong metal-ring bond in the cobalt complex is presented. Reaction of (R4C4)Co(CO)2Br with C6F5Li gave the very stable (R4C4Co(CO)2C6F5. With aromatic hydrocarbons in the presence of AlCl3, (R4C4)Co(CO)2Br gave the stable [(R4C4)Co(π-Arene)]+; cycloheptatriene also reacted with (R4C4)Co(CO)2Br in the absence or a catalyst to give [(R4C4)Co(C7H8)]+. Nucleophilic attack occurred readily at the C7H8 ring in [(R4C4)Co(C7H8)]+ and less readily at the benzene ring in [(R4C4)Co(C6H6)]+ to give (R4C4)Co(cycloheptadienyl) and the (R4C4)Co(cyclohexadienyl) complexes, respectively.</p> <p> The order of susceptibility of π-complexed ligands in metal d^8 complexes towards nucleophilic attack, cycloheptatriene> benzene> (R4C4)> cyclopentadienyl, is proposed. A novel method for effecting hydride abstraction is reported. Aniline in [(Ph4C4)Co(π-Aniline)]+ is less basic than aniline itself by approximately 1.5 pK units.</p> / Thesis / Doctor of Philosophy (PhD)

Thesis advisor: Marc L. Snapper / Chapter 1: The design of a novel first aid smart fabric that is linked to a biologically active molecule through an event specific cleavable linker is described. Successful functionalization of a cellulose filter paper fabric mimic and the synthesis of a linker which is potentially selectively cleavable in the presence of blood have been achieved. Chapter 2: Synthetic studies towards the total synthesis of Torilin, a sesquiterpene guaiane natural product with interesting biological activities are described. The synthesis of the hydroazulene core of Torilin is accomplished through a cyclopropanation/ Lewis acid mediated fragmentation of a highly functionalized polycyclic system which is rapidly accessed through the intramolecular cycloaddition of cyclobutadiene. / Thesis (MS) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

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Thesis advisor: Marc L. Snapper / Intramolecular cycloadditions of cyclobutadiene provide rapid access to rigid polycyclic systems with high strain energies and unique molecular geometries. Further functionalization of these systems followed by strain-release fragmentation provides great opportunities to construct fused-medium-ring architecture, which are very common in natural products but challenging to achieve efficiently. An intermolecular cyclopropanation/acid-mediated rearrangement strategy has been previously developed to access the 5-7 bicyclic ring systems in a highly stereospecific manner. The application of this strategy is being studied for the synthesis of a biologically interesting guaiane natural product: torilin. In a complementary fashion, an intramolecular cyclopropanation/thermal rearrangement sequence is developed to access two different molecular frameworks of 5-7-5 tricyclic ring systems. A library of functionalized 5-7-5 tricyclic ring systems can be systematically built up from the same starting material for potential future use in high-throughput screening. / Thesis (PhD) — Boston College, 2012. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Thesis advisor: Marc L. Snapper / Cyclobutadiene cycloadditions provide rapid access to rigid polycyclic systems with high strain energy and unusual molecular geometries. Further functionalization of these systems allows entry into unexplored chemical space. A tricarbonylcyclobutadiene iron complex on solid support enables exploration of these cycloadditions in a parallel format amenable to diversity oriented synthesis. Modeling of the cycloaddition transition states with density functional calculations provides a theoretical basis for analysis of the regioselectivity observed in generation of these substituted bicyclo[2.2.0]hexene derivatives. The high strain energy accessible in cyclobutadiene cycloadducts and their derivatives renders them useful synthons for access to medium-ring natural products through ring expansion. Torilin, a guaiane sesquiterpene isolated from extracts of the fruits of <italic>Torilis japonica</italic>, exhibits a range of biological activities including testosterone 5&alpha;-reductase inhibition, hKv1.5 channel blocking, hepatoprotective, anti-inflammatory and anti-cancer effects. These activities are reviewed and analyzed from the perspective of a common biochemical target. Tandem oxidation and acid-catalyzed rearrangement of a highly strained tetracyclo[5.3.0.0<super>1,5</super>.0<super>2,4</super>]decane in the presence of tetrapropylammonium perruthenate provides the bicyclo[5.3.0]decane core of this natural product with complete control of relevant stereochemistry. The complex precursor required for this rearrangement is rapidly accessed by cyclopropanation of an intramolecular cyclobutadiene cycloadduct. Synthetic studies are reported which provide preliminary access to 8-deoxytorilolone. / Thesis (PhD) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.