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Biology and Chemistry Research was indicative of an aliphatic CH stretch, and the carbonyl peak at 1720 cm−1 was indicative of the successful addition of the acid chloride. Strong absorbance at 1350 cm−1 was also indicative of the nitro group, which provides additional evidence for a successful synthesis. The next step in this synthetic plan was the reduction of the nitro group to an amine. This reduction was accomplished using stannous chloride dihydrate as described by Bellamy [18,19]. The purified product from the previous reaction was combined in a 1:5 molar ratio with SnCl2·2H2O in ethyl acetate. This reaction mixture was then heated to 70◦C and stirred for one hour. The majority of SnCl2·2H2O was removed using gravity filtration, and the remaining reaction mixture was washed with brine and then dried over sodium sulfate. TLC showed the sample to be relatively pure, and thus no further purification was necessary. Solvent was evaporated using a rotary evaporator, and the sample was then massed to calculate yield. IR spectroscopy was once again used for structural verification, and there was clear indication of a primary amine with absorbance at 3364 cm−1. This reaction yields the product seen in figure 8.
The final reaction involved the oxidation of the thiol to form a disulfide dimer of figure 8, thus producing the molecule seen in figure 5. This was accomplished by stirring the thiol in a solution of dichloromethane under an oxygen atmosphere at slight positive pressure for 20 hours, producing a near quantitative yield of the disulfide. Final structural verification was carried out using proton and carbon-13 NMR. After this first synthesis, a second scale-up synthesis was completed to verify results and test scale-up feasibility. For the benzoyl chloride esterification, all amounts were quintupled, and reaction time was increased to 4.5 hours. Column purification failed with a ethyl acetate:hexane eluent due to poor product solubility in this mixture. To rectify this, a 3:2 mixture of dichloromethane and hexane was used. The nitro reduction reaction was run using an identical procedure. However, the final oxidation of the thiol to a disulfide was done using a new procedure, using hydrogen peroxide catalyzed with potassium iodide, adapted from Kirihara et al [20]. Molar equivalents of the thiol and 30% H2O2 solution were combined in the presence of one mole percent KI and stirred for 4 hours in 10 mL of ethyl acetate at room temperature. Extraction was preformed using ethyl acetate, washed once with deionized water and three times with brine. The resulting organic layer was dried over sodium sulfate, and then solvent was removed using a rotary evaporator. 2.3 Instrumentation All infrared spectra were acquired using a Shimadzu FTIR 8400S. Eighty scans were run to yield accurate spectra. An attenuated total reflectance (ATR) adapter was used to allow for the analysis of the solid samples. Proton and C13 NMR were obtained using an Anasazi EFT-60 spectrometer. The proton spectra were collected running 128 scans at 60.01 MHz. Carbon-13 spectra were collected with 32,768 scans at 15.089MHz. Both scans were collected on approximately 30 mg of product dissolved in deuterated chloroform. These spectra were created using equipment at an off-site academic institution due to the lack of instrumentation available locally. 3. Results and Discussion 3.1 Molecular Modeling and Structure Determination The MolDock virtual docker engine generated hundreds of potential poses for each of the eight potential ligands modeled. For each pose generated, numerous parameters are considered, including hydrogen bond energies, electron affinity, cofactor interactions, and many more. All of these parameters are combined to create the rerank score, which is designed to accurately predict relative binding affinity for a number of different ligands. Table 1 shows the top pose for each of the eight tested ligands and the associated Volume 3 | 2013-2014 | 43