Proligands chiral

When we utilized the chiral proligand in an identical reaction, we... 

Although hydroamination of allenes can be easily achieved with group 4 and group 5 metal catalysts, the stereoselectivity of these systems is rather limited. Several attempts to perform asymmetric hydroamination/cyclization of aminoallenes employing chiral aminoalcohols [260, 261] and sulfonamide alcohols [262] as chiral proligands for titanium- and tantalum-based catalyst systems have produced vinyl pyrrolidines with low selectivities only. While the titanium catalysts were... 

This means that each proligand is achiral or chiral in isolation. When chiral, a pair of enantiomeric prohgands in isolation is represents by a pair of an alphabet and an overlined alphabet, e.g., p and p shown in Fig. 10.1. Differentiation between reflections and i S -permutations is essential to constmct stereoisograms (Fujita 2004d,a,c). In addition, hgand reflections are created as operations of another type by operating reflections and i 5-permutations successively. 

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