| Judging from current chemical literature, many research groups are making efforts to minimize the amount of waste generated as a result of chemical reactions. Use of methods focused on catalytic processes are one of many approaches to achieving this goal. More specifically, using reduced amounts of catalytic organometallic reagents (e.g., catalytic copper hydride) has become a more prevalent and practical way to effect conjugate reductions of alpha,beta-unsaturated carbonyl systems. Copper hydride-catalyzed tandem conjugate reduction/alkylation chemistry has successfully been developed as a means at arriving at beta-hydroxy ketones and/or related derivatives. Chemical yields of this process are good and the overall transformation, normally considered a two pot process, has been reduced to a one-pot sequence.; Asymmetric hydrosilylation has enjoyed a rich history within asymmetric catalysis employing several metal-based catalysts (e.g., Rh, Ru, and Ti). Much of the success of this chemistry has resulted from creative design of nonracemic ligand scaffolds. Copper hydride catalyzed asymmetric hydrosilylation has not received equal attention and new advances have been made using bis-phosphine ligated-CuH as the source of chirality. Development of especially mild and efficient means of reducing prochiral ketones in a 1,2-sense with CuH afford competitive enantioselection, and recent realization of substrate:ligand (S:L) levels of ≥100,000:1 have been documented, far better than any currently reported values.; Development of novel nonracemic ligands continues to drive asymmetric catalysis. The advent of 1,1'-binaphthyl constructs ( e.g., BINAP and NOBIN) has provided exceptional means for which to transfer chiral information to prochiral substrates. The use of a nonracemic tether to control stereoselective biaryl couplings has been further exploited towards the improved synthesis of cyclo-NOBIN. The chiral tether has also provided a means for attachment of novel cyclo-NOBINs to a solid support, and application towards asymmetric alkylation and asymmetric transfer hydrogenation chemistry, utilizing both homogenous and heterogeneous reagents, has been described. |
