Selective synthesis and reactivity of eta5-arylcyclohexadienyliron complexes.
A series of aryl-substituted cyclohexadienyliron complexes have been prepared by a general procedure that determines regioselectivity by correctly positioning leaving groups in the precursor complexes. The aryl groups at 1-C or 2-C have been shown to be omega directing by the study of reactions with a representative range of nucleophiles, and these regioselectivity properties have been related to the spectroscopic properties of the cationic cyclohexadienyliron complexes. A high level of electron-donating substituents on the arene, or switching between the [Fe(CO)3] and [Fe(CO)2PPh3] series, reduces the minor ipso pathway, improving regiocontrol. Placing opposed directing groups in the arylcyclohexadienyliron complexes reverts reactivity to the ipso pathway with stabilised enolate nucleophiles, and when the additional directing group reinforces the effect of the aryl group, the ipso pathway is stopped.
Owen
David A
DA
Wolfson Materials and Catalysis Centre, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich, NR4 7TJ, UK.
Malkov
Andrei V
AV
Palotai
Ian M
IM
Roe
Caroline
C
Sandoe
Elizabeth J
EJ
Stephenson
G Richard
GR
D006575:Heterocyclic Compounds, 3-Ring / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure
D006575:Heterocyclic Compounds, 3-Ring