Fan, Y.; Kass, S. R. “Electrostatically Enhanced Thioureas”, Org. Lett. 2016, 14, 188-191
A new class of readily prepared thiourea catalysts with one or more positively charged centers and no new hydrogen-bonding sites are exploited in several bond-forming reactions and are orders of magnitude more reactive than Schreiner’s thiourea. These findings provide the basis for a new strategy for activating hydrogen-bond catalysts.