Asymmetric Deactivation of Racemic Catalysts

Whilst non-racemic catalysts can generate non-racemic products with or without the NLE, racemic catalysts (0% ee) inherently produce only racemic (0% ee) products. A strategy whereby a racemic catalyst is enantiomer-selectively deactivated by a chiral molecule as a catalyst poison has recently been reported to yield non-racemic products (Fig. 7-3) [46 8]. A unique resolution of racemic CHIRAPHOS has been attained with a chiral iridium complex to give a deactiva- 

Enantiomerically pure diisopropoxytitanium tartrate can also be used as a poison for racemic binaphthol-derived titanium diisopropoxide (2) (Eqs. (7.16) and (7.17)) [48d,e]. The % ee of the product increases with an increase in the amount of DIPT employed. 

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