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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Approaches to the synthesis of 2-hydroxyquinolines

Dwyer, Catherine Lynn 06 September 2012 (has links)
M.Sc.
92

Consecutive palladium-mediated reactions in the synthesis of some bicyclic systems

Williams, Dennis Bradley Glen 11 February 2014 (has links)
M.Sc. (Chemistry) / Palladium-mediated carbon-earbon (and carbon-heteroatom) bond formation! is to an increasing extent playing a vital role in synthetic organic chemistry. The chemistry is usually performed under mild conditions, with the organopal1adium intermediates being formed in situ from inorganic palladium salts or complexes, and has good tolerance of functionality on the substrates. The palladium mediator may be present in the reaction in amounts ranging from stoichiometric to catalytic. Reactions requiring stoichiometric amounts of palladium may appear to be inherently uneconomical. Palladium, however, may be easily recovered in most cases, and may be converted into salts useful for catalysis, effectively offsetting the initial expense. 2 The use of polymer-bound palladium catalysts! has also been shown to be a viable method of palladium recovery. Palladium may form a- or 1r-eomplexes with organic compounds and, as with many other transition-metal complexes, a-palladium complexes are generally only stable in the presence of select ligands. Arylphosphines are most commonly used, and of these triphenylphosphine is the ligand of choice for its availability and low cost...
93

The total syntheses of dregamine and epidregamine : a general route to 2-acylindole alkaloids

Sung, Wing Lam January 1977 (has links)
A general method for the total synthesis of 2-acylindole alkaloids is outlined and its application to the syntheses of dregamlne (34) and epidregamine (181) described. 2(S)-Amino-3(β-indolyl)-propan-l-ol (113), prepared from L-(-)-tryptophan (112) by lithium aluminum hydride reduction, was converted to its ditosylate (114). Reaction of the latter with potassium cyanide afforded 3(S)-tosylamino-4-(β-indolyl)-butanonitrile (115) which was transformed to 3(S)-amino-4(β-indolyl)-butanonitrile (116) by reductive cleavage. Formylation of (116) with methyl formate afforded 3(S)-(N-formylamino)-4-(β-indolyl)-butanonitrile (117). From this stage, a number of routes directed towards the synthesis of either a vobasine or sarpagine system were investigated. The only successful sequence involved initially a Bischler-Napieralski type reaction of (117) with polyphosphate ester (PPE) as the reagent whereupon the 3-dihydrocarboline derivative, 3(S)-cyanomethyl-3,4-dihydro-β-carboline (160) was obtained. The latter compound was then condensed with 3-methylenepentan-2-one (121) under acidic conditions to afford four isomeric 6(S)-cyanomethyl-3-ethyl-2-oxo-l,2,3,4,6,7,12,12b-octahydroindolo-(2,3-a)-quinolizines (159A-D). These isomers can be interconverted by acidic, basic or thermal methods, and therefore all of these compounds are useful for subsequent synthetic reactions. Base catalysed transannular cyclization of the 3(S), 12b(S)-isomer (159D) gave 16(R)- and 16(S)-cyano-16-descarbomethoxy-19,20(S)-dihydro-15(R)-hydroxypericyclivine (164) and (165), the latter possessing the desired sarpagine skeleton. Both the nitriles (164) and (165) were utilized for the subsequent experiments. Reaction of (164) with cyanogen bromide provided the 3(R) and 3(S)-N-cyano-16(R)-cyano-16-descarbomethoxy-19,20(S)-dihydro-15(R)-hydroxyperivinols (173) and (174), while (165) under these conditions afforded the 3(S), 16(S)-diol (170). Manganese dioxide oxidation of both (173) and (174) afforded N-Cyano-16(R)-cyano-16-descarbomethoxy-19,20(S)-dihydro-15(R)-hydroxyperivine (175) and the latter was converted to N-cyano-16(S)-cyano-14,15-dehydro-16-descarbomethoxy-19,20(S)-dihydroperivine (172) by thionyl chloride dehydration and subsequent treatment with sodium hydroxide. The diol (170) in the other series was converted to the same ketone (172) through the same procedure. Sodium borohydride (pyridine) treatment of (172) accomplished the simultaneous reduction of the unsaturated carbonyl system and removal of the N-CN group to provide 16(S)-cyano-16-descarbomethoxy-19, 20(S)-dihydroperivinol (176) which was oxidised by manganese dioxide to give its corresponding ketone (177). Alkaline hydrolysis of the latter and subsequent esterification yielded 16-epi-19, 20(S)-dihydroperivine (179). The latter compound is identical with an authentic sample prepared from the alkaloid perivine (23) by hydrogenation and epimerization of the ester group. N-methylation of (179) by the Eschweiler-Clarke procedure and in turn, dregamine (34) after (181). provided 16-epidregamine (181) base-catalysed epimerization of (181). / Science, Faculty of / Chemistry, Department of / Graduate
94

Approaches to the synthesis of structures related to shikimic and chorismic acids.

Mane, Jean Maurice. January 1976 (has links)
Thesis: M.S., Massachusetts Institute of Technology, Department of Chemistry, 1976 / Includes bibliographical references. / M.S. / M.S. Massachusetts Institute of Technology, Department of Chemistry
95

Total synthesis of ḏḻ-camptothecin.

Bradley, Joel Chandler. January 1975 (has links)
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 1975 / Vita. / Includes bibliographical references. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Chemistry
96

Synthesis of polymethylene-diphosphines

Ong, Beng Soon January 1974 (has links)
No description available.
97

Preliminary study on the synthesis of withaferin A.

Tsui, Paulus Tsang-kwong. January 1968 (has links)
No description available.
98

Bridged analogs of N-benzoyl phenylalanine esters : synthesis and interactions with proteases

Elie, Patrick January 1977 (has links)
No description available.
99

Synthesis of some 1,4-glycosans.

Manca, Adriano January 1972 (has links)
No description available.
100

The total synthesis of a cepham derivative.

Rossy, Phillip Andrew. January 1972 (has links)
No description available.

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