Thiohydantoins microwave-assisted synthesis

Muccioli, G.G., Poupaert, J.H., Wouters, J. etal. (2003) A Rapid and Efficient Microwave-Assisted Synthesis ofHydantoins and Thiohydantoins. Tetrahedron, 59, 1301-1307. 

Muccioli GC, Poupaert JH, Wouters J, Norberg B, Poppitz W, Scriba GKE, Lambert DM (2003) A rapid and efiBcent microwave-assisted synthesis of hydantoins and thiohydantoins. Tetrahedron 59 1301-1307... 

A one-pot synthesis of thiohydantoins has been developed using microwave heating [72]. A small subset of p-substituted benzaldehydes, prepared in situ from p-bromobenzaldehyde by microwave-assisted Suzuki or Negishi reactions, was reacted in one pot by reductive amination followed by cyclization with a thioisocyanate catalyzed by polystyrene-bound dimethyl-aminopyridine (PS-DMAP) or triethylamine, all carried out under microwave irradiation, to give the thiohydantoin products in up to 68% isolated yield (Scheme 16). 

The microwave-assisted one-pot three-step synthesis of thiohydantoins has been studied together with a polymer-supported catalyst and/or reagent [55]. Cyclization of a number of AT-substituted amino acids of type 50 and thioiso-cyanates 51 has given satisfactory yields within 5 min at 170 to 180 °C (see Scheme 29). Polymer-supported dimethylaminopyridine (PS-DMAP) 52 has been utilized as a supported base herein to catalyse the reaction however, in most cases the yield was comparatively lower to the use of triethylamine (TEA). PS-DMAP also assisted in simplifying the purification. 

K. Eaghihi, K. Zamani, A. Mirsamie, M.R. Sangi, Microwave-assisted rapid synthesis of novel optically active poly(amide-imide)s containing hydantoins and thiohydantoins in main chain. Europ. Poly. J. 39, 247-254 (2003)... 

---