Chiral, metal-free Brønsted bases have been demonstrated capable of catalyzing several types of C–C and C–X bond-forming reactions with high chemical and stereochemical efficiency, thereby complementing other major organocatalytic asymmetric approaches such as enamine catalysis. This critical review describes the most fundamental developments in the area, which have been documented in the last couple of years, along with major mechanistic implications. Discussion includes the limitations of the present protocols, identifies the most salient gaps, and gives a prospect of future improvements and applications (122 references).
21 September 2015 in Angewandte Chemie International Edition
Planar chirality is one of the most fascinating expressions of chirality, which is exploited by nature to lock three‐dimensional chiral conformations and, more recently, by chemists to create new chiral reagents, catalysts, and functional organic materials. Nevertheless, the shortage of procedures able to induce and secure asymmetry during the generation of these unique chiral entities has dissuaded chemists from exploiting their structural properties. This Minireview intends to illustrate the limited but remarkable catalytic methods that have been reported for the production of planar chirality in strained molecules and serve as a source of inspiration for the development of new unconventional procedures, which are expected to appear in the near future.