Silylated cyclohexadiene reducing agent

Silylated 1,4-cyclohexadienes were introduced as reducing agents in radical chain reactions such as dehalogenation, deoxygenation via thionocarbonate ester and deselenization [120]. Two examples are given in Reactions (4.75)... 

Scheme 4.8 Silylated cyclohexadienes as radical-based reducing agents...

Silylated 1,4-cyclohexadienes were used to replace tin hydride as reducing agents in radical chain reactions. They were prepared by TBDMSCl interception of the regioselec-tive metallation intermediate of cyclohexadienes, and subsequent methylation (eq 40). The 3-TBDMS-2,4-dimethoxy-l,4-cyclohexadiene was found to be a very efficient hydrogen donor reagent in various radical reactions. 

Studer and co-workers have used silylated cyclohexadienes as radical chain reducing agents for the reduction of 44 to 45. Release of RjSi followed by re-aromatization is the driving force of the reaction. These reagents can be easily prepared and initiation can be performed with AIBN, triethylborane/02 or by simply using an air atmosphere. 

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