Iron-catalysed hydrofunctionalisation of alkenes and alkynes
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Date
26/11/2015Item status
Restricted AccessEmbargo end date
31/12/2100Author
Greenhalgh, Mark David
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Abstract
The iron-catalysed hydrofunctionalisation of alkenes and alkynes has been developed to give
a range of functionalised products with control of regio-, chemo- and stereochemistry. Using
a bench-stable iron(II) pre-catalyst, the hydrosilylation, hydroboration, hydrogermylation
and hydromagnesiation of alkenes and alkynes has been achieved.
Iron-catalysed hydrosilylation, hydroboration and hydrogermylation of terminal, 1,1- and
1,2-disubstituted alkyl and aryl alkenes and alkynes was developed, in which the active iron
catalyst was generated in situ (Scheme A1). Alkyl and vinyl silanes and pinacol boronic
esters were synthesised in good to excellent yield in the presence of a range of functional
groups. Catalyst loadings as low as 0.07 mol% were demonstrated, along with catalyst turn-over
frequencies of up to 60 000 mol h−1. The iron-catalysed formal hydrocarboxylation of a range of styrene derivatives has been
developed for the synthesis of α-aryl carboxylic acids using carbon dioxide and
ethylmagnesium bromide as the stoichiometric hydride source (Scheme A2). Detailed
mechanistic studies have shown this reaction proceeds by iron-catalysed hydromagnesiation
to give an intermediate benzylic organomagnesium reagent. The nature of the active catalyst
and reaction mechanism have been proposed.