Progress in Catalytic Asymmetric Protonation

Abstract

AbstractEnantioselective protonation represents an appealing approach for the construction of nonracemic chiral tertiary carbon centres, frequently found in a large range of bio‐relevant organic compounds. The development of efficient catalytic processes has hitherto been regarded as a challenging goal for the synthetic chemist. Significant developments in catalytic enantioselective protonation (EP) that have been emerging over the last few years (2009–2013) are presented in this microreview. These include not only catalytic EP processes from preformed enol derivatives and useful tandem Michael addition/protonation sequences, but also unprecedented catalytic cascade reactions involving enantioselective protonation as a crucial stereo‐determining step. Here, special attention is paid to the scope and limitations of these new catalytic EP processes, while valuable mechanistic insights into the catalytic cycles and into the key enantioselective protonation steps are provided.