Reactions driven by activation of allylic halides.

摘要

The utility of indium metal as well as indium Lewis acids in organic synthesis has received a great deal of interest due to their relatively low toxicity, stability in air and water, and recyclability. Due to distinctive advantages of indium over other metals, we have applied indium reagents in organic synthesis. Indium metal and indium Lewis acids have been utilized in a variety of reactions. We have lately discovered that a catalytic amount of indium(III) salt is capable of activating an allyl halide. We have successfully applied such an activation to construct a variety of cyclic molecules by In(III)-catalyzed atom transfer cyclizations, In(III)-catalyzed ring-closing Friedel-Crafts reactions, and catalytic O-alkylations. In addition, we have developed a practical synthesis of chiral amines via asymmetric organoindium addition to hydrazones. Chiral amines are one of the most useful synthons in the synthesis of many biologically active molecules. In particular, the availability of chiral tert-carbinamines is limited, and their synthesis remains a difficult problem with few solutions. We have discovered a useful solution by utilizing asymmetric indium allylation of ketimines. We also applied this methodology to enantio- and diastereoselective organoindium addition to hydrazones. We have obtained high yield and excellent enantioselectivity.