Bower’s compound

Both enantiomers of the biologically active Bower s compound, a potent analogue of an insect juvenile hormone [103] (Scheme 18) were prepared using Aspergillus sp. cells in 96% ee. Interestingly, biological tests showed that the (6i )-antipode was about ten times more active than the (6S)-counterpart against the yellow meal worm Tenebrio molitor. 

Scheme 18. Application of fungal epoxide hydrolase to the synthesis of (R)- and (S)-Bower s compounds...

Synthesis of both enantiomers of Bower s compound using whoie cells of Aspergillus niger LCP 521 as a biocatalyst. 

Archelas, A., Delbecque, J.R and Furstoss, R. (1993) Microbiological transformations. 30. Enantioselective hydrolysis of racemic epoxides the synthesis of enantiopure insect juvenile hormone analogs (Bower s compound). Tetrahedron Asymmetry, 4,2445-2446. 

Both enantiomers of Bower s compound, a potent analog of an insect juvenile hormone [161] (Scheme 20), were prepared in 96% e.e. using A. niger epoxide hydrolase. Interestingly, subsequent biological tests revealed that the (6R) antipode was about 10 times more active than the (6S) conterpart against the yellow mealworm Tenebrio molitor. 

The lignin model compounds and their derivatives used in this study were custom synthesized at Queen s University by Dr. R. Bowers (Colour Your Enzyme). CIDEP and conventional ESR experiments were conducted using either a Varian E-104 spectrometer or a customized Bruker X-band spectrometer, modified similarly as previously described (7). The light source used for in situ irradiation was either a super high pressure 200 W mercury lamp, a Lambda-Physik EMG101-MSC XeCl excimer laser at 308 nm., or a Quanta-Ray GCR-11 Nd YAG solid state laser equipped for all four harmonic generations. 

The formation of molecular radical ions by electron transfer reactions between alkali metals and a wide variety of aromatic and other organic compounds in polar solvents is well established. A very large number of radical anions have been prepared by this method and extensive studies of their e.s.r. and optical spectra have been made (Bowers, 1965 Gerson, 1967 Kaiser and Kevan, 1968). In solution the electron transfer reaction will be facilitated by the subsequent solvation of the two ions (or ion pair) by the polar solvent molecules. However, we have observed that similar electron transfer reactions occur readily when alkali metal atoms are deposited on a variety of relatively non polar substances at 77°K in the rotating cryostat. In most cases the parent compound acts as the matrix, though for some radical ions an inert matrix of a non-polar hydrocarbon has been used successfully. It is perhaps surprising that the reactions occur so readily as the energy of solvation of the ions must be quite small in most of these systems as compared with that in the polar liquids. 

Bowers and Greene (1963) reported the e.s.r. spectrum of the radical-anion of cyclopropane and Bowers ealkali-metal reduction of the parent compound. However, Gerson et al. (1966) have found that none of these compoimds is reduced under these conditions (i.e. the e.s.r. signal due to the solvated electron is not quenched) and Jones (1966) has foimd that the signal from the supposed adamantane radical-anion is that of the benzene radical-anion. 

C. Zerner, Michael J. Scott and C. Russell Bowers. He then joined Michael B. Hall s research group at Texas A M University and is currently an Assistant Research Scientist. His research focuses on using theoretical and computational chemistry to research and answer questions in a variety of areas, including biological enzyme catalysis, catalytic and stoichiometric mechanisms of bond activation and functionalization of organic molecules by organometallic transition metal complexes, and the elucidation of structure and bonding of various compounds of interest. 

Bowers, W. S., Insecticidal compounds from plants, in Phytochemical Resources for Medicine and Agriculture (H. N. Nigg and D. S. Seigler, eds.), 227-235, Plenum Press, New York, 1992. 

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