Distribution of Catalytic Species as an Indicator To Overcome Reproducibility Problems.

Irreproducibility is a common issue in catalysis. The ordinary way to minimize it is by ensuring enhanced control over the factors that affect the reaction. When control is insufficient, some parameters can be used as indicators of the reaction performance. Herein we describe the use of the distribution of catalytic species as an indicator to map, track, and fine-tune the performance of catalytic reactions. This indicator is very sensitive and presents a quick response to variations in the reaction conditions. We have applied this new strategy to the conjugate addition of C-nucleophiles to enals via iminium intermediates, consistently achieving maximum turnover frequencies (TOF) regardless of the quality of the starting materials used. In addition, the present method has allowed us to efficiently reduce the catalyst loading to as little as 0.1 mol %, the lowest one described for this kind of reaction.