Thiol-ene Chemistry

Thiol-ene reactions involve the addition of a S-H bond across a double or triple bond by either a free radical or ionic mechanism. Thiol-ene reactions are essentially the sulfur version of the hydrosilylation reaction.

Because the reactions are efficient, high yielding, and tolerant of various solvents and functional groups, many researchers now consider the thiol-ene reaction to be a "click" reaction.

We have found the thiol-ene reaction to be an excellent method for derivatizing unsaturated organosilicon and organic compounds. We recently reported the synthesis of a variety of functional organosilicon compounds from thiol-ene reactions of tetravinylsilane with commercially available thiols. Representative examples are shown below. Yields ranged from 64 to 100%.

  • Rissing, C.; Son, D. Y. "The Thiol-ene Reaction for the Synthesis of Multifunctional Branched Organosilanes", Organometallics 2008, 27, 5394-5397. Link

These compounds were prepared by irradiating solutions of tetravinylsilane and the thiol in open flasks. Ordinary borosilicate glassware can be used. Our light source was a simple sunlamp:

We are also investigating the application of these compounds as cores for divergent dendritic growth. Our results indicate that thioether dendrimers up to the fifth generation can be prepared using thiol-ene chemistry (3rd generation dendrimer shown below).

  • Rissing, C.; Son, D. Y. "Application of Thiol-ene Chemistry to the Preparation of Carbosilane-thioether Dendrimers", Organometallics 2009, 28, 3167-3172. Link

We have used the carbosilane-thioether dendrimers to stabilize Ag nanoparticles through chemical reduction, UV irradiation, or simple heating.

  • Son, D. Y.; Rissing, C.; Chen, L.; Andersson, T. E. "Thiol-ene Chemistry for the Synthesis and Modification of Branched Organosilicon Polymers", Polymer Preprints 2010, 51(2), 730-731. Link
  • Chen, L.; Andersson, T.E.; Rissing, C.; Yang, S.; Chen, S.; Son, D. Y. "Irradiation- and thermoinduced synthesis of Ag nanoparticles within amphiphilic carbosilane thioether dendrimers", Journal of Materials Chemistry B 2013, 1, 116-122. Link
  • Zhang, J.; Lin, L.; Wang, C.; Chen, S.; Chen, L.; Son, D. Y. "Versatile Dendrimer-Derived Nanocrystal Microreactors towards Fluorescence Colloidal Photonic Crystals", Journal of Materials Chemistry C 2014, 2, 3610-3616. Link

Using ionic thiol-ene (thiol-Michael) chemistry, we derivatized 1,3,5-triacryloylhexahydro-1,3,5-triazine (TAT) in high yields and short reaction times. Very little purification of the products was necessary.

  • Rim, C.; Lahey, L. J.; Patel, V. G.; Zhang, H.; Son, D. Y. "Thiol-ene reactions of 1,3,5-triacryloylhexahydro-1,3,5-triazine (TAT): facile access to functional tripodal thioethers", Tetrahedron Letters 2009, 50, 745-747. Link

We obtained good quality single crystals of one of the products. The X-ray crystal structure indicated the formation of capsule-like dimers connected in a linear chain. Hydrogen bonding plays an important role in the solid state structure.

We are currently investigating the application of these and related compounds as chelating ligands and ion recognition agents. We have also extended this chemistry to the synthesis of star-shaped oligomers, again using TAT as a core.

  • Rim, C.; Son, D. Y. "Facile and efficient synthesis of star-shaped oligomers from a triazine core", Tetrahedron Letters 2009, 50, 4161-4163. Link

We recently discovered a route to multifunctional thiols through the selective reaction of mercaptoalcohols with chlorosilanes. Representative examples are shown below. Yields were generally good to excellent.

  • Jennings, A. R.; Son, D. Y. "Multifunctional thiols from the highly selective reaction of mercaptoalcohols with chlorosilanes", Chemical Communications 2013,49, 3467-3469. Link

Through a collaboration with Professor Walter Voit at the University of Texas at Dallas, these multi-thiols are being used for the preparation of degradable thiol-ene substrates.

  • Ware, T.; Jennings, A. R.; Bassampour, Z. S.; Simon, D.; Son, D. Y.; Voit, W. "Degradable, silyl ether thiol-ene networks for implantable electronics", RSC Advances 2014, 4, 39991-40002. Link