Simplex optimization was used to maximize the production of Maillard reaction compounds which inhibit the growth of Staphylococcus aureus. The simultaneous factor shift and mapping procedures of the optimization program enabled the optimization to be completed with a minimum number of experiments. The reaction conditions likely to have the greatest effect on the production of these compounds were chosen as: (1) molar ratio of amino acid to sugar, (2) total concentration of reactants, (3) pH, (4) temperature and (5) time of heating. Inhibition of the test organism was quantified as the radius of no growth, by the concurrent use of the variable and uniform cams of the spiral plating system. Twenty nine experiments were required to reach the optimum of model system A, glucose + lysine, while model system B, xylose + lysine, was optimized after 28 experiments. The minimum inhibitory concentration (MIC) of the optimum glucose + lysine reaction mixture was 5.78 x 10⁻⁴ μg/cfu, while that of the xylose + lysine reaction mixture was 8.94 x 10⁻⁴ μg/cfu. Multiple regression analysis of the data indicated that pH and total concentration were the two most significant factors in determining the inhibitory compounds produced by the glucose + lysine mixture. Molar ratio, temperature and time were not significant for this combination of reactants. The most significant factors for the xylose + lysine combination were pH and temperature, whereas molar ratio and total concentration were not significant. Calculation of the contributing proportion (Pⅰ) of each variable to the response, supported the results of the regression analysis. Separation of the optimized Maillard reaction mixtures according to molecular weight, using ultrafiltration, failed to provide any information about the molecular weight range of the inhibitory compounds. / Land and Food Systems, Faculty of / Graduate

The photochemistry of a variety of tetrahydro-1,4-naphthoquinones (structure 1) has been investigated. These were synthesized by Diels-Alder reaction of corresponding p-quinones and acyclic-1,3-dienes [diagram omitted]. Three substituent-dependent types of reactions were observed: (1) for adducts possessing hydrogen substituents at C₄a and C₈a (bridgehead position), the prevalent process was one of abstraction of a β-hydrogen atom from C₅(or equivalently, C₈) by excited carbonyl oxygen. In general, three product types were then observed, derived from carbon-carbon bond formation (proceeded in two instances by conformational rotation about the C₄a - C₈a bond) in the bisallylic radical so produced. Placing a methyl or phenyl substituent at C₂ renders the β-hydrogens non-equivalent, and abstraction occurs in accord with expectations based on the formation of the more stable biradical intermediate. In adducts possessing bridgehead substituents, rotation about the C₄a - C₈a bond in the biradical is suppressed and only a single product type (enone alcohol) is formed, which possesses the same relative conformation as the biradical and starting adduct. In the case where the bridgehead substituents are carboxymethyl, however, secondary photolysis in benzene solution occurs, giving rise to a product where the bridgehead substituents are nearly eclipsed. (2) For the adduct possessing exo-methyl substituents at positions 5 and 8 as well as methyls at the bridgehead positions and at and C₂ and C₃, hydrogen abstraction was partially suppressed in favor of a process tentatively concluded to involve Ύ~hydrogen abstraction by excited enone carbon, giving rise to a product, the formation of which again requires little conformational change in the biradical. (3) For adducts possessing endo-methyl substituents at C₅ and C₈ as well as bridgehead substituents, a novel oxetane product was observed, formally the result of a cycloaddition reaction involving the remote double bond and one of the carbonyl groups. The oxetane derived from the duroquinone adduct was found to be photolabile, giving back starting material and, eventually, a quantitative conversion to a novel cage diketone. The reactivity differences for these systems, as well as for those previously studied in our laboratory, are interpreted as being due to the effects of substituents on the energy barrier to conformational isomerization in the biradical intermediates. Finally, the potential utility of these photochemical reactions for the synthesis of unusual ring systems is noted. / Science, Faculty of / Chemistry, Department of / Graduate

The preparation of allenes by the condensation of an acyl chloride with a phosphonium ylid and subsequent elimination of an acid salt and a phosphonium oxide has been established by Bestmann and Hartung. It was felt that this process could be expanded to include the synthesis of butatrienes. Butatrienes are stabilized by aromatic substituents while aromatic substituents decrease the nucleophilicity and reactivity of the phosphonium ylids to be used in the synthesis of the butatrienes. The ylids employed were carbomethoxyphenylmethylenetriphenyl phosphorane, and a new compound, carbethoxyphenylmethylenetriphenyl phosphorane, both of which failed to form alkylated condensation products. Both ylids were prepared by the "melt" method which gave better yields than comparable processes in dry benzene. The salt of a third ylid, carbethoxyphenylmethylenetrimethylphosphonium chloride - a new compound, was also prepared. However, the process for the preparation of this salt was not consistently reproducable and gave only low yields. A previously unreported reaction involving the condensation of ethyl diethylphosphonoacetate and benzoyl chloride was carried out and led to the formation of ethyl phenylpropynoate as was proposed.

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