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Preparation of Chiral Homoannularly Bridged N,P‐Ferrocenyl Ligands by Intramolecular Coupling of 1,5‐Dilithioferrocenes and Their Application in Asymmetric Allylic Substitution Reactions
Author(s) -
Fukuzawa Shinichi,
Yamamoto Masahisa,
Hosaka Mitsuteru,
Kikuchi Satoshi
Publication year - 2007
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200700470
Subject(s) - chemistry , intramolecular force , ferrocene , allylic rearrangement , cyclopentadienyl complex , medicinal chemistry , amination , ligand (biochemistry) , tsuji–trost reaction , palladium , substitution reaction , ring (chemistry) , stereochemistry , catalysis , organic chemistry , receptor , electrochemistry , biochemistry , electrode
Homoannularly bridged ferrocene 6b was prepared by intramolecular coupling of 1,5‐dilithioferrocene 5b mediated by Fe(acac) 3 . Dilithioferrocene 5b was prepared by lithium–halogen exchange of the corresponding diiodide, which was prepared by 1,5‐dilithiation of the o ‐TMS‐blocked ferrocene and followed by trapping with iodine and removal of the TMS group. Alternatively, 5b could be readily prepared by the reaction of o ‐bromophenylferrocene 8 with n BuLi (>2 equiv.). The benzene ring of 6b underwent ortho lithiation with t BuLi, and the resulting lithiated species was trapped with Ph 2 PCl to produce corresponding aminophosphane 7d . Aminophosphane 13 , which has the phosphanyl group on the cyclopentadienyl ring, was prepared by intramolecular coupling of 1,5‐dilithiated PhPPFA 11 mediated by Fe(acac) 3 . New N,P ligands 7d and 13 were used in the palladium‐catalyzed allylic alkylation and amination of 1,3‐diphenyl‐2‐propenyl acetate ( 14 ), and ligand 7d was found to give good yields with enantioselectivities as high as 96 % ee . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)