Radical 9-borabicyclo nonane

Stannyl radicals are usually generated by homolytic substitution at hydrogen in a tin hydride, or at tin in a distannane, or, conjugatively, at the y-carbon atom in an allylstannane.453 The initiator is commonly AIBN at ca. 80 °C. In the presence of a trace of air, organoboranes are oxidized by a radical chain mechanism, and triethylborane is now commonly used as an initiator at temperatures down to —78°C,519 and it can be used in aqueous solution.520 9-Borabicyclo[3.3.1]nonane (9-BBN) has similarly been used to initiate the reaction of tin hydrides at 0 and —78°C,521 and diethylzinc works in the same way.522... 

Photocatalytic carbonylative coupling with 9-alkyl-9-borabicyclo[3.3.1]-nonanes (9-R-9-BBN), however, made it possible to transform alkyl halides to ketones [72]. lodoalkenes or iodoalkynes are thus cyclized to five-membered rings [73]. The oxidative addition of iodoalkyl to palladium(O) proceeds via radicals allowing the ring closure to take place prior to the dual coupling with CO and the alkylboranes. 

Triethylboron and 9-borabicyclo[3.3.1]nonane (9-BBN) are good radical sources for certain synthetic procedures. The reactions involve oxidation of the borane. 

The photoelectron spectrum of 9-(9-borabicyclo[3.3.1]nonyl)-9-azabicyclo-[3.3.1]nonane (46) shows two low-energy ionizations. Furthermore, cyclic voltametry suggests that the lifetime of the radical cation is short, which does not conform with expectation based upon Bredt s rule of kinetic stability. Mass spectral fragmentation patterns have been reported for compounds of types (47) and (48). ... 

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