Perdeutero-spiropentane (C₅D₈) has been synthesized and infrared and Raman spectra are reported for the first time. Wavenumber assignments are made for most of the fundamental vibrational modes. Gas phase infrared spectra were recorded at a resolution (0.002 cm⁻¹) sufficient to resolve individual rovibrational lines and show evidence of strong Coriolis...
Studies toward the total syntheses of highly potent cytotoxic alkaloids
including the bromopyrrole alkaloids and indole alkaloids were conducted and are
described. Studies carried out in the course of this dissertation consist of five total syntheses of natural products that include bromopyrrole alkaloids nagelamide A, D and agelastatin D as...
Many D2d-symmetric 2,2',6,6'-tetrasubstituted biphenyls are
readily prepared via net oxidative dimerization of appropriate
1,3-disubstituted benzenes. Conversion of such proprochiral
compounds to useful C2-symmetric chiral biphenyls requires
formal replacement of two substituents on opposing aryl ring
units with alternate groups. This under exploited
desymmetrization tactic has been demonstrated for the
generation...
Traditional approaches for the direct preparation of alkenes are unable to fully control either the stereochemical configuration of the carbon-carbon double bond or else the regiochemistry of the substituents surrounding it. The recently introduced concept of carbenoid eliminative cross-coupling (CEXC) offers a remedy to these deficiencies by providing for a...
The inert gas ion bombardment of solid surfaces has
found many uses in the field of analytical chemistry. In
one method of spectrochemical analysis, inert gas ion
bombardment in a glow discharge is used to produce an atomic
vapor, representative of the sample bulk, which is analyzed
using atomic absorption...
I. Lithium alkyl and aryl monosubstituted cyclooctatetraenide
dianions (Li₂ C₈H₇-R; R = methyl, n- butyl, sec- butyl, tert- butyl,
phenyl and benzyl) were synthesized by the reaction of the appropriate
organolithium reagent with cyclooctatetraene in diethyl ether or
tetrahydrofuran. The reaction occurred cleanly and with good yield
of lithium monosubstituted...
Studies towards the total synthesis of (+)-Phomactin A (1), D (6), and G (9), fungal metabolites with unique molecular architecture and pronounced biological activity, are described. These studies resulted in the synthesis of advanced intermediates 354 and 356, which contain all of the carbon atoms of 1, 6 and 9....
The enantioselective total synthesis of quinolizidine-containing natural product cermizine D and formal syntheses of senepodine G and cermizine C has been achieved. These natural products are members of the lycopodium alkaloids, which have attracted significant attention due to their exciting biological activities and the diverse structural scaffolds. Key steps in...
The atmospheric trace element abundances associated with slash
burning have been measured by instrumental neutron activation analysis
(INAA). On site ground level samples were collected during the slash
burning season using high volume samplers and a cascade impactor. In
addition to the air samples, soil, wood and ashed wood samples...
We have developed a compact micro total analysis system (μTAS) to serve as a platform for in-situ spectrophotometric water quality monitoring. Individual fluidic, optical, and electrical components were designed, developed, and characterized. These components were combined in both an integrated (single lithographic “chip-based” platform) and a modular manner. The microfluidic...
Irradiation of a tryptamine linked through its side-chain nitrogen to an alkylidene malonate residue results in an intramolecular [2 + 2] cycloaddition to the indole 2,3-double bond. The resultant cyclobutane undergoes spontaneous retro-Mannich fission to produce a spiro[indoline-3,3-pyrrolenine] with relative configuration defined by the orientation of substituents in the transient...
This thesis describes the development of a new enantioselective synthetic method employing chiral cis-2,5-diaminobicyclo[2.2.2]octane-based organometallic catalysts. The significance of this new method to organic synthesis is illustrated with preparation of enantioenriched products that are transformed to important pharmaceutical agents. Chapter 1 provides a brief historical overview of asymmetric catalysis, especially...
The total synthesis of a highly potent cytotoxic marine natural product, phorboxazole A, is described. Both a palladium(II)-mediated and a palladium(II)-catalyzed intramolecular alkoxycarbonylation were used as key steps for the preparation of the two cis-2,6-disubstituted tetrahydropyran rings (C22-C26 and C11-C15) of phorboxazole A.
The synthesis used a convergent approach involving...
Studies toward the total synthesis of (+)-providencin (1), a highly oxygenated cembranoid dipterpene with a unique bicyclo[12.2.0]hexadecane skeleton and pronounced biological activity, are described. These studies resulted in the synthesis of advanced intermediates 320 and 332 which contain all of the carbon atoms of 1. In a first generation approach...
Studies towards the total synthesis of (−)-kendomycin (1), a bacterial metabolite with
a unique molecular architecture and pronounced biological activity, are described. These
studies resulted in the synthesis of advanced intermediate 208, containing all of the
carbon atoms of 1.
A Dötz annulation between alkyne 122 and novel chromium carbenoid...
Ion-selective polymeric optical sensors – ion optodes – are a promising alternative to ion-selective electrodes and fluorescent dyes for analytical and biological applications, e.g. extra- and intracellular measurements. They are non-toxic, highly selective robust probes for ionic fluxes monitoring.
A large-scale fabrication of ion optodes using a solvent displacement method...
Neptunium, with its rich redox chemistry, has a special position in the chemistry of actinides. With a decades-long history of development of aqueous separation methods for used nuclear fuel (UNF), management of neptunium remains an unresolved issue because of its not clearly defined redox speciation. Neptunium is present in two,...
Avermectin Bia is a member of a class of medicinally important
natural products known for its potent antiparasitic activity and
interesting structural features. In this thesis, synthesis of a
model for the spiroketal portion of the avermectins is presented.
Oxidation of (S)-2-methylbutanol, followed by a stereoselective
chromium mediated reaction with...
A method for the control of absolute stereochemistry in
morphine syntheses has been demonstrated by the resolution
and efficient racemization of the advanced morphine precursor , 9-methoxy-3-methyl-5,6-dihydro-3H-benzofuro[3,2-e]isoquinoline-
7(7aH)-one, I. This was accomplished by the facile coversion of optically resolved I to its ring opened
form, 5,6,7,8-tetrahydro-10-methoxy-3-methyl-7-oxo[1]benzoxonino[
6,7-c]pyridinium tosylate, II, (Equation...
Interesting rovibrational characteristics of two D_(3h) oblate symmetric top molecules were studied. Hamiltonian models for the fine rovibrational level structure of [1.1.1]propellane (propellane) were obtained for many low-lying modes. Ground state parameters (GSP) that are not exclusively K^(2n) dependent were obtained. Initially, the GSP were used in conjunction with density...
The first asymmetric synthesis of (-)-7-epicylindrospermopsin via intramolecular nitrone cycloaddition is described. The synthesis utilized a convergent approach to prepare the cycloaddition precursor 176, which was assembled by condensation of hydroxylamine 175 with aldehyde 145. Hydroxylamine 175 was synthesized from ethylene glycol (166) in seven steps. Aldehyde 145 was completed...
The stereocontrolled synthesis of the southern lactone 17 of
boromycin and of the northern segments of both boromycin and aplasmomycin
are described. The syntheses begin with enantioselective
epoxidation of 3-buten-2-ol (42) to provide the optically active
2(S),3(R) epoxy alcohol 43. The absolute configuration was confirmed
by preparing 43 from (-)-2,3-dihydroxybutyric...
Part I. The total synthesis of (+)-leptosphaerin (2), a metabolite of the marine
Ascomycete Leptosphaeria Oraemaris (Linder) was achieved, unambiguously
establishing both the relative and absolute stereochemistry of this natural product. This
synthesis also resolved the long-standing question of which of the isomeric structures 1
or 2 correctly represents the...
Several approaches to the synthesis of methymycin were
investigated. Segment A (39), containing functionality corresponding
to C-9, 10, and 11 of methynolide was made in
six steps from propionaldehyde in an overall yield of 37%.
Oxidation of 34 with silver nitrate gave 35 which, upon hydroxylation
with hydrogen peroxide, gave...
The production cross sections for a number of target fragments
formed by the reactions of 42- and 21- GeV²⁰ Ne and 28 GeV p with ¹⁸¹Ta have been measured. The target fragment radioactivities were
measured by off-line gamma-ray spectroscopy. Details of the measurement
as well as the calculation of the...
Studies were carried out to determine the absolute stereochemistry of
botryococcene (1). The natural product was degraded to two sets of 'y- and 8-
valerolactones. All enantiomeric variations of these lactones were synthesized in
optically pure form starting from (S)- and (R)-methyloxiranes. 1H NMR correlation of
natural and synthetic materials...
The fusion reaction ²⁰⁸Pb (⁵⁰Ti, xn) ²⁵⁸⁻x Rf (x = 1-3) was studied to determine PCN (probability that the mononucleus system evolves to form a compound nucleus inside the fission saddle point) and to establish the value of Wsur (survival probability) for the given reaction experimentally. The fission excitation function...
Avermectins are a group of potent anthelmintic agents produced by Streptomyces avermitilis. They are active at extremely low dosages and are now in commercial use. In this study, the synthesis of two segments of avermectin B[subscript 1a] are described. The synthesis of the hexahydrobenzofuran subunit (segment A) began with the...
A formal total synthesis of the macrolactone pyrolizidine alkaloid (-)-integerrimine (2), from R-(+)-citronellal (93) is described. Aldehyde 93 was converted to exo methylene derivative 94 which was reduced to allylic alcohol 95. The epoxides 96 and 98, obtained in a ratio of 3:1 respectively by Sharp less epoxidation of 95...
A comparative study was made on the effect of urea denaturation
of bovine serum albumin (BSA), polyglycyl BSA and poly-L-phenylalanyl
BSA. The denaturation process was followed by ultraviolet
spectrophotometry and optical rotation.
A blue shift in the absorption maximum at 278 mμ was observed
in urea denatured proteins, In 7M...
The design and construction of a chemiluminescence
photometer is described. The design is based on a discrete
sample system which has a number of advantages over
the previously described flow cell system and centrifugal
analyzer. The advantages include simple and inexpensive
equipment, small sample size, versatile electronic readout
system, and...
The development and optimization of a single-phase derivatization
technique for small ring aromatics in water are presented. Also
described are the design, optimization and application of a remote
reaction chamber for fiber optic sensing.
Aqueous solutions of the major aromatic compounds in gasoline are
derivatized to o-nitrosophenol-Cu complexes with a...
The mycosporins, formerly called P310's are secondary metabolites
of fungi closely associated with fungal reproductive processes that
require light. The structurally related iminomycosporins are found in
marine plants and animals and may also have functions related to
light. In this study, approaches toward the asymmetric synthesis of
the mycosporins are...
Studies toward synthesis of subunits of sanglifehrin A, an immunosuppressant featuring a highly substituted [5,5]-spirolactam moiety as well as a 22-membered macrocycle are described. The macrolactone contains a peptidic backbone characterized by an unusual [beta]-substituted (S)-piperazic acid and (S)-m-hydroxyphenylalanine units. These studies resulted in the synthesis of advanced intermediate 358...
¹³⁰ Sn and ¹²⁸Sn were separated from mixed fission products.
The decay of these isotopes were studied with Ge(Li),
LEPS, and plastic scintillator detector systems in single
and two parameter coincidence modes. The decay scheme constructed
for ¹²⁸Sn decay has levels at 0.0 (5+), 45.7 (4+),
77.8 (3+), 152.9 (2+),...
A convergent synthesis of epothilone B that generates all seven of its
asymmetric centers in a completely stereoselective fashion has been
completed. Key reactions include an anti-Felkin aldol condensation to
set the C6 and C7 stereochemistry, a directed α-hydroxylation to install
the C15 (S)-hydroxyl substituent, and a Wittig condensation to...
A large-scale preparative method for potassium di-n-butylborate
in triethylamine solvent has been developed. The reaction of
potassium di-n-butylborate I with trifluoromethyl iodide has been
shown to yield trifluoromethyl di-n-butylborane and other products.
Reaction of this substance with boron trifluoride gave trifluoromethyl
boron difluoride. Reactions of diboron tetrafluoride, boron tribromide,
and...
Four strategies which involve synthetic elaboration of
the shikimate nucleus are discussed. Methyl shikimate was
differentially protected as the 3,4-0-cyclopentylidene ketal
and as the 5- 0- tert- butyldiphenylsilyl ether. The methyl
ester was then reduced with diisobutylaluminum hydride and
the resulting allylic alcohol was oxidized to aldehyde 47
with pyridinium...
Studies toward the total synthesis of a highly potent cytotoxic marine natural product, phorboxazole A, were conducted and resulted in a route to an advanced intermediate, C4-C32, for this purpose. A key feature of our approach is the stereoselective synthesis of two cis-2,6-disubstituted tetrahydropyrans present in the macrolide portion of...