Guanidine-thiourea bifunctional organocatalyst for the asymmetric Henry (nitroaldol) reaction

Novel bifunctional catalysts having guanidine and thiourea functional groups were developed for the asymmetric Henry (nitroaldol) reaction. Various structural developments of the catalyst revealed that the compound having an octadecyl-substituted guanidine and thiourea groups linked with a chiral spacer derived from phenylalanine, i.e., 1e, efficiently promoted the Henry reaction. This bifunctional organocatalyst le also gave high asymmetric inductions C, with aliphatic cyclic aldehydes and branched aliphatic aldehydes (82-90% ee).