Cyclohexadiene palladium catalyzed asymmetric

Table 4 Palladium-catalyzed asymmetric hydrosilylation of cyclohexadiene 38...

The palladium catalyzed asymmetric hydroamination of cyclohexadiene with arylamines utilizing a variant of Trost s ligand R,R) 61 proceeds with high enantio selectivities under mild conditions (Scheme 11.19) [21]. The mechanism is believed to follow a similar pathway as proposed for palladium catalyzed hydroamination of vinyl arenes (Scheme 11.2) [17]. 

Scheme 11.19 Palladium catalyzed asymmetric hydroamination of cyclohexadiene [21].

In a recent study, a significant improvement was accomplished in the asymmetric palladium-catalyzed 1,4-hydrosilylation of cyclic 1,3-dienes with the use of chiral ligand (/ )-MOP-phen (Scheme 8-2) [18]. Thus hydrosilylation of cyclopentadiene gave 5 in 99% yield with an enantiomeric excess of 80%, which is the highest reported ee value for Pd-catalyzed hydrosilylations of 1,3-dienes. With 1,3-cyclohexadiene, the yield of the... 

In the asymmetric hydrosilylation of 1,3-cyclohexadiene 38 (Scheme 10, Table 4), catalyzed by chiral ferrocenylphosphines 5 and 40, the enantioselectivity is higher with phenyldifluorosilane than that with trichlorosilane or methyldichlorosilane (entries 1—4). The reaction of 38 with phenyldifluorosilane in the presence of a palladium catalyst coordinated with ferrocenylphosphine 40b gave allylsilane (A)-39c with 77% ee.58,59 The use of (j3-N-sulfonylaminoalkyl (phosphine 35a for the reaction of 38 with methyldichlorosilane exhibited the same level of asymmetric induction (entries 5-6).53 In this asymmetric hydrosilylation, combination of trichlorosilane and... 

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