Search

The first example of manganese-catalyzed asymmetric transfer hydrogenation of N-heteroaromatics in water is reported. This ATH reaction proceeds smoothly without the need for inert atmosphere protection in the presence of a water-stable manganese catalyst, which bears an easily available aminobenzimidazole ligand. Ammonia borane, regarded as a green, cheap and high atom economical hydrogen source, was applied. Various quinolines are transformed into the desired products in high yields and up to 99% enantiomeric excess (ee). The utility of the current protocol was demonstrated by applying it in the gram-scale total synthesis of the Hancock alkaloid (−)-cuspareine with 96% overall yield. [ABSTRACT FROM AUTHOR]

3d-Metal catalyzed borrowing hydrogen (BH) reactions represent powerful and environmentally friendly approaches for the direct coupling of alcohols with nitriles to assemble various important branched nitriles. The development of simple and efficient ligands is a crucial issue in this field. In this study, we designed a series of readily available N , N -bidentate ligands that demonstrated good efficiency in the Mn-catalyzed BH reaction of alcohols and nitrile derivatives, yielding the targeted nitriles in moderate to good yields. Remarkably, the mildness and practicality of this protocol were further demonstrated by the successful synthesis of anipamil via a two-cascade borrowing hydrogen procedure., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)