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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 26, Number 9
BKCSDE 26(9)
September 20, 2005 

Chiral [Iminophosphoranyl]ferrocenes: Synthesis, Coordination Chemistry, and Catalytic Application
Thanh Thien Co, Sang Chul Shim, Chan Sik Cho, Dong-Uk Kim, Tae-Jeong Kim*
Chiral ferrocenes, Iminophosphoranes, N ligand, Palladium catalysts, Allylic alkylation
A series of new chiral [iminophosphoranyl]ferrocenes, {η5-C5H4-(PPh2=N-2,6-R2-C6H3)}Fe{η5-C5H3-1-PPh2-2-CH(Me)NMe2} (1: R = Me, iPr), {η5-C5H4-(PPh2=N-2,6-R21-C6H3)}Fe{η5-C5H3-1-(PPh2=N-2,6-R2-C6H3)-2-CH(Me)R2} (2: R1 = Me, Pr; R2 = NMe2, OMe), and (η5-C5H5)Fe{η5-C5H4-1-PR2-2-CH(Me)N=PPh3} (3:R = Ph, C6H11) have been prepared from the reaction of [1,1'-diphenylphosphino-2-(N,N-dimethylamino) ethyl]ferrocene with arylazides (1 & 2) and the reaction of phosphine dichlorides (R3PCl2) with [1,1'- diphenylphosphino-2-aminoethyl]ferrocene (3), respectively. They form palladium complexes of the type [Pd(C3H5)(L)]BF4 (4-6: L = 1-3), where the ligand (L) adopts an η2-N,N (2) or η2-P,N (3) as expected. In the case of 1, a potential terdentate, an η2-P,N mode is realized with the exclusion of the ?P=NAr group from the coordination sphere. Complexes 4-6 were employed as catalysts for allylic alkylation of 1,3-diphenylallyl acetate leading to an almost stoichiometric product yield with modest enantiomeric excess (up to 74% ee). Rh(I)-complexes incorporating 1-3 were also prepared in situ for allylic alkylation of cinnamyl acetate as a probe for both regio- and enantioselectivities of the reaction. The reaction exhibited high regiocontrol in favor of a linear achiral isomer regardless of the ligand employed.
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