Steve Farmer

Assistant Professor of Organic Chemistry

E-Mail: farmers@sonoma.edu

Office: 316 Darwin

My CV

Research:

     My main area of research involves developing and utilizing ring contracting sulfur extrusion routes for the carbazole ring structure.  Due to a lack of efficient techniques for this conversion, my initial efforts focused on creating effective methods of the conversion of phenothiazine to carbazole.  I have had some success, generating three methods for the high yield conversion of phenothiazine to carbazole (Li/PPh₃, Li/Na & Degassed Raney Nickel) and two methods for the first ever reported ring contracting sulfur extrusion of phenothiazine-5-oxide and phenothiazine-5,5-dioxide (Li/Na and Degassed Raney Nickel). Currently, I am interested in exploiting these new methods for the synthesis of interesting compounds containing the carbazole ring structure.

     An interesting use of these new desulfurization methods would be generating a general synthesis routes to natural products with the carbazole ring structure.  There has been a strong interest in carbazole by chemists and biologists due to the intriguing structural features and promising biological activities exhibited by such carbazole alkaloids as hyellazole, carbazomycin, ellipticine and murrayafoline A.  A possible ring contracting desulfurization synthesis pathway for murrayafoline A is shown in Scheme 1.  This pathway represents an improvement on the current literature methods because it is a step shorter.  Also, it forms the central pyrrole ring last, which will allow for the substituents on both benzene rings to be easily changed. 

Scheme 1. A synthesis pathway to murrayafoline A.

     Another area of my research interests involves grafting polymer chains from the surface of organic crystals to form core/shell nanoparticles.  Although the idea of grafting polymer chains from the surface of inorganic nanoparticles, such as silica, is well known, no work has been done grafting polymer chains from the surface of organic crystals. 

     The characterization of these nanoparticles will involve the use of instruments well known for organic molecules, such as NMR, FTIR and UV/Vis, along with some more specific instruments for polymers and nanoparticles, such as gel permeation chromatography (GPC), scanning electron microscopy (SEM) and atom force microcopy (AFM).  Once this technique is developed, a wide variety of functional organic molecules, such as porphyrins or organic dyes, can be incorporated into the organic crystal core.

     Once encapsulated, the organic crystal/polymer nanoparticles can be suspended in the organic solvents required for many film forming processes, without the possibility of the core organic crystals dissolving.  Typically when an organic crystal containing polymer film is created, the film is formed first and then the organic crystals are grown inside during a subsequent process.  Polymer encapsulated organic crystals will allow this film forming process to be accomplished in one step.  Also, these polymer encapsulated organic nanocrystals could provide an interesting new method for drug delivery.

Scheme 2.  The synthesis of organic crystal/polymer core/shell nanoparticles.