Organometallic chemistry

Cyclopheophorbides absorb light at higher wavelengths (> 670 run) as compared
to their precursor pyropheophorbides ( ~ 666 run) and are strong antioxidants. Therefore
they could potentially be used as photosensitizers in photodynamic therapy, although this
study does not focus on the pharmacology aspect of this class of compounds.
The overall goal of this study was to hemisynthesize, purify and characterize
certain cyclopheophorbides from both chlorophyll a and b families. The known
hemisynthesis of 13^2,17^3-cyclopheophorbide a enol was repeated. A major success in the
purification process was achieved by utilizing polystyrene divinylbenzene (PS-DVB
a.k .a. PRP-1 TM) as the stationary phase in reversed phase flash chromatography. Altering
(TMS)2-NNa with (TMS)2-NLi was found to increase yields. 13^2,17^3 -mesocyclopheophorbide a enol was successfully hemisynthesized as a
novel compound.
Methyl-3-devinyl-3-[1-hexyloxy]ethyl pyropheophorbide a (HPPH-ME), was
prepared, purified and molecular characteri zation on the compound was performed. Hemisynthesis ofHPPH-CYCLO from HPPH-ME was attempted, but was
unsuccessful.
Zinc and copper pyropheophorbide a methyl esters were prepared with the intent
of forming of zinc and copper CYCLO. Hemisynthesis of corresponding metalloCYCLO
from both insertion of the metal inside the CYCLO core and cyclizations of
metal derivatives of pyropheophorbide a methyl ester were unsuccessful.
Chlorophyll b was successfully extracted from green algae Chiarella and purified
in mg lots (100%) utilizing RP-LPLC and with a binary solvent gradient program.
Pheophorbide b methyl ester and pyropheophorbide b methyl ester were made and
characterized. Hemisynthesis of CYCLO-b was unsuccessful likely due to the altered
reactivity of pyropheophorbide b (vs. -a) methyl ester. To reduce the reactivity, reduction
of formyl group of pyropheophorbide b methyl ester with NaBH4 was performed. Still,
formation of a CYCLO derivative was not achieved.
Chromatographic purification, mass and NMR characterization of CYCLO,
mesoCYCLO, HPPH-ME and all precursor compounds are reported. 2D NMR of most of
these compounds are reported here for the first time.

We report here the development of a Lewis acid catalyzed method for the dehydrative
coupling of cyclic alcohols and nitriles to form amides with retention of configuration.
By contrast, the formation of amides by nitrile trapping of carbocations (Ritter reaction)
usually affords racemic product. The present reaction was accomplished by first
converting alcohol starting materials to their corresponding chlorosulfites in situ. Even
after an extensive search, only copper (II) salts were able to produce the desired
conversion of these chlorosulfites to amides though with low catalytic turnover.
Improving the turnover without deteriorating the stereochemical outcome was eventually
accomplished by a careful selection of the reagent addition sequence and through the
removal of gaseous byproducts. This Ritter-like coupling reaction proceeds in good
yields with secondary cyclic alcohols under mild conditions. The stereochemical outcome likely due to fast nucleophilic capture of a non-planar carbocations (hyperconjomers)
stabilized by ring hyperconjugation.

New organometallic containing materials were synthesized by the reaction of Group IVB metallocene dichlorides of the form Cp2MCl2 where M = Ti, Ar, and Hf with Hematoporphyrin IX using the interfacial condensation polymerization technique. The structural characterization was accomplished using infrared and mass spectroscopy and elemental analysis. The results obtained from these techniques showed the presence of the metal ester and ether bonding as evidence that the reaction occurred. The product derived from titanocene dichloride, 12-A, exhibited growth inhibition characteristics towards the Candid albicans and Staphylococcus aureus microorganisms. From the preliminary metal adsorption studies it was shown that this product also bound nickel ions.