Giese method radical addition reactions

Radical addition reactions conducted by the mercury(II) hydride method were also pioneered by Giese and are very similar in principle to the tin hydride method. The radical is generated from an organomer-curial (rather than a halide) and removed by hydrogen transfer from a mercury(II) hydride (rather than a tin hydride). Mercury(II) hydride reductions have been covered in several recent reviews.3,5,81,82... 

Curran2 has reviewed recent applications of the tin hydride method for initiation of radical chain reactions in organic synthesis (191 references). The review covers intermolecular additions of radicals to alkenes (Giese reaction) as well as intramolecular radical cyclizations, including use of vinyl radical cyclization. 

Efforts to compare fliis model with the MCP model have been hindered by the fact that similar composition curves for a given system are predicted by both models. Hill et al." showed that the composition data of Dodgson and Ebdon for STY/MAH at 60°C could be equally well described by flic MCP, MCD or penultimate unit models. They suggested that sequence distribution would be a more sensitive tool for discriminating between these models. One study which lends some support to this model over the MCP model for describing this system was published by Ratzsch and Steinert. Using Giese s" mercury method to study the addition of monomers to primary radicals, they found that in mixtures of MAH and STY, only reaction products from the addition of free monomers, and not the EDA... 

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