j131By contrast, metal-free organocatalysts [6] can be viewed as an attractive alternative to those processes in which the metal is not vital for the key bond-forming event. The advantages are obvious: no metal leaching to the product, reduced toxicity, and lower cost of the catalysts and their regeneration. Therefore, the prime goal here is to develop new, robust processes that could compete with their established, metalcatalyzed counterparts.Silanes are widely recognized as efficient reagents for reduction of carbonyl and heterocarbonyl functionality. In the case of alkyl-and arylsilanes, the reaction requires catalysis by Lewis acids or transition metal complexes [1,3]; however, with more Lewis acidic trichloro-or trialkoxysilanes, an alternative metal-free activation can be accomplished. Thus, it has been demonstrated that extracoordinate silicon hydrides, formed by the coordination of silanes to Lewis bases, such as tertiary amines [7a], DMF [7b] or MeCN, and so on [7], can serve as mild reagents for the reduction of imines to amines [8]. In the case of trichlorosilane, an inexpensive and relatively easy-to-handle reducing reagent, and DMF as a Lewis basic promoter, the intermediacy of hexacoordinate species has been confirmed by 29 Si NMR spectroscopy [7b]. Formamides as Lewis-Basic Organocatalysts in Hydrosilylation of IminesScheme 4.2 Preparation of amines by asymmetric reduction of imines generated from prochiral ketones. For R 1 , R 2 , and R 3 , see Tables 4.