| Autor: |
R Cox, Liam, V. Ley, Steven |
| Zdroj: |
Chemical Society Reviews; September 1, 1998, Vol. 27 Issue: 5 p301-314, 14p |
| Abstrakt: |
π-Allyltricarbonyliron lactone complexes, η4-dienetricarbonyliron complexes and their relatives offer an interesting approach to the problem of acyclic stereocontrol. Functional groups appended to the organic ligand frequently adopt a preferred conformation. This, combined with the steric bulk of the Fe(CO)3 moiety provides a means for controlling the addition of reagents to such pendant functionality in a defined manner. Thus addition of nucleophiles to aldehydes and ketones affords a route to diastereoisomerically pure secondary and tertiary alcohols while olefinic functionality in the side-chain can be utilised in stereoselective dihydroxylations, Diels–Alder and Michael addition reactions. Just as the formation of arene Cr(CO)3 complexes modifies reactivity at the α-position of arene substituents, the Fe(CO)3 group of η4-diene and trimethylenemethane tricarbonyliron complexes can be used to stabilise an adjacent positive charge. Trapping of the carbocation resulting from ionisation of an α-carbinol occurs with high diastereoselectivity, providing an unusual and useful stereoselective SN1-type reaction. Such highly stereoselective reactions have been put to good use in the preparation of a number of biologically interesting natural products. |
| Databáze: |
Supplemental Index |
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