Synthesis of novel camphor-derived bifunctional thiourea organocatalysts.

Synthesis and catalyst performance of 2,3- (types and ) and 2,8-disubstituted (type ) thiourea bifunctional organocatalysts was attempted. The synthesis of catalyst of type has, so far, not been realized, while catalysts of type , i.e., the 2,3-exo- and the 2-endo-3-exo-thiourea catalysts, were prepared in six steps starting from (+)-camphor. The catalysts of type were prepared from (+)-camphor in eight steps. All the potential catalysts as well as most of the intermediate products were carefully structurally characterized. The thiourea bifunctional organocatalysts were tested in a model reaction of Michael addition of dimethyl malonate to trans-β-nitrostyrene.