UC Santa Barbara

Over the past two centuries, the field of organic chemistry has expanded to facilitate transformations for the synthesis of complex molecular scaffolds of increasing variability. With these advancements, however, the dependence on organic solvents as reaction medium remains. This research describes a general alternative to organic solvents by employing the designer surfactant, TPGS-750-M, under aqueous conditions, which spontaneously assembles to form micellar aggregates (nanoreactors) providing conditions under which organic transformations favorably take place. Key features of this technology include: low reaction temperatures, the ability to recycle the reaction medium (and often the catalyst), as well as low production of organic waste as quantified by Sheldon’s E Factors.

Under micellar catalysis conditions it was discovered that nanoparticle-catalyzed reactions are especially well suited to take place including the Z-selective semi-reductions of alkynes as well as nitro-group reductions that take place at room temperature with exceptional yields and selectivity. Both systems undergo reduction by the use of borohydride salts as the hydride source allowing these procedures to take place under ambient conditions. An environmentally responsible method for amide and peptide bond synthesis is also described, not only replacing egregious organic solvents such as DCM and DMF, but also eliminating the need for explosive HOBt by incorporation of an oxime activator, Oxyma, in the form of uronium coupling reagent COMU.

Furthermore, as an ultimate goal of this chemistry is to minimize potential waste on scale, procedural modifications are described by the incorporation of minimal co-solvents for a survey of reaction types. These modifications investigated impact on reaction yield, rate, and physical aspects of a reaction mixture such that technology developed in lab can reach its highest potential when considered on an industrial scale.