Theses and Dissertations at Montana State University (MSU)
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Item Expanding the scope of allylbis(silane)-imine cyclizations : a concise approach to the synthesis of the azatricyclic core of Stemofoline and Asparagamine A(Montana State University - Bozeman, College of Letters & Science, 2015) Anderson, Bryon Keith; Chairperson, Graduate Committee: Thomas S. LivinghouseThe Mannich cyclization has been utilized for the synthesis of a number of heterocyclic compounds since its discovery. In this dissertation, a silane-based variant of the Mannich cyclization is discussed. This Mannich-like cyclization has proven to be a powerful tool in governing regio- and stereo- control in carbon-carbon bond forming reactions, which benefit from enhanced nucleophilicity of the C=C pi bond derived from the hyperconjugative effect of the adjacent silicon group. Despite the synthetic utility associated with this transformation, there are comparatively few examples that have explored the intramolecular variant containing silane-based nucleophiles. The utility of a 2-propylidene-1,3-bis(silane) nucleophile in synthesis has also received little attention and it is the goal of this project to further develop this concept, and to apply these findings toward the construction of the azatricyclic core found in the stemona alkaloids Asparagamine A and Stemofoline. The use of a 2-propylidene-1,3-bis(silane) nucleophile in N-acyliminium ion chemistry has been successfully applied towards the construction of the azatricyclodecane cores by employing two cationic desilylative cyclization events. Construction of the requisite nucleophile was accomplished in quantitative yield through a Negishi coupling which employed ZnCl 2 x (THF) 2 and 7 mol% PdCl 2(PPh 3) 2. Within this linear synthesis the enantiopure cores were acquired in 16% (36) and 12% (38) overall yield (16 and 17 steps respectively) from 1,1-dibromo-4-amino-1-butene (18).Item Part 1: study toward the total synthesis of acutumine ; : Part 2: asymmetric intramolecular hydroamination catalyzed by group 3 metal complexes(Montana State University - Bozeman, College of Letters & Science, 2014) Huynh, Khoi Quang; Chairperson, Graduate Committee: Thomas S. Livinghouse; Tao Jiang and Tom Livinghouse were co-authors of the article, 'Substrate structural effect in Y(III)-catalyzed hydroamination/cyclization of 1,2-disubstituted and 1,1,2-trisubstituted aminoalkenes terminated by 2-(2-heteroarenyl) groups' in the journal 'Synlett' which is contained within this thesis.; Tom Livinghouse and Helena Lovick were co-authors of the article, 'N,N'-dibenzosuberyl-1,1'binaphthyl-2,2'-diamine. A highly effective supporting ligand for the enantio-selective cyclization of aminoalkenes catalyzed by chelating diamide complexes of La(III) and Y(III)' in the journal 'Synlett' which is contained within this thesis.Acutumine 1 is a tetracylic alkaloid isolated from Menispermum daurcum, which exhibits selective T-Cell cytotoxicity. It is potentially useful for specific therapy T-Cell related Leukemia and lymphoma. Acutumine is a highly functionalized tetracyclic natural product, containing a [4.3.3]-propellane core and a 5,5-spirocycle. The synthesis of the 5,5-spirocycle is prepared via enantioselective Pd II/IV catalyzed chloro-induced semi pinacol rearrangment. However, studies showed Pd catalyst functioned as Lewis acid to oxidant, PhI(OAc) 2 rather than forming a Pi-complex with the substrate as proposed. Fortunately, the preparation of the spirocycle can be accomplished from an asymmetric Pd II /Brønsted acid cocatalyzed semi pinacol rearrangement via direct allylic C-H activation. [4.3.3] propellane core was concisely synthesized in eight step sequences featuring a phosphoric Brønsted acid catalyzed aldol condensation and radical N-cyclization as the key transformations. Hydroamination, the addition of an amine N-H bond across an unsaturated carbon-carbon linkage, allows a highly atom economical access to industrial and pharmaceutical important alkaloids. The hydroamination of alkene by early transition metal has seen significant process. Herein, we reported the substrate structural effect in Yttrium(III)-catalyzed intramolecular hydroaminations. Aminoalkenes possessing a terminal 2- (5-trimethylsilyl)thienyl group exhibited substantially enhanced reactivity. Cyclization efficiency for a representative aminoalkene possessing a Z-configured 2-(phenyl)ethenyl group is considerably higher than that observed for the corresponding E-isomer. Enantioselective hydroamination/cyclization of representative aminoalkenes catalyzed by chelating diamide complexes of La(III) and Y(III) are described. The La(III) complex derived from the sterically demanding (R)-N,N'-dibenzosuberyl-1,1'-binaphthyl-2,2'-diamine proligand provides enantioselectivities that are in many cases significantly higher than those obtained with the corresponding Y(III) analog.Item A total synthesis of dendrobine(Montana State University - Bozeman, College of Letters & Science, 1991) Lee, Cheol HaeItem Acylnitrilium ion-arene spiroannulations : studies toward the synthesis of the Lycopodium alkaloid serratine(Montana State University - Bozeman, College of Letters & Science, 1994) Luedtke, Gregory RandallItem Development and synthetic application of the allylbis (silane) cyclization terminator(Montana State University - Bozeman, College of Letters & Science, 1997) Kercher, Timothy Scott