Access to NHC-Boryl Mono- and Bis-Selenide and Utility as Mild Selenium Transfer Reagent Including to the C-F Bond.

Reactions of 5-SIDipp ⋅ BH (5-SIDipp=1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene) (1) with diphenyldiselenide provide access to 5-SIDipp-boryl mono- (5-SIDipp ⋅ BH SePh) (2) and bis-selenide (5-SIDipp ⋅ BH(SePh) ) (3). The facile cleavage of the B-Se bond makes 2 a neutral source of selenium nucleophiles in substitutions reactions with benzyl bromides, and provide access to the corresponding selenoethers. The direct transformations of one of the C(sp )-F bonds of C F N and C F CF to C-Se bonds have also been achieved by the use of 2 without employing transition-metal catalysts. While it was previously established that C F could undergo complete defluoroselenation under harsh conditions, we successfully achieved partial defluorination of C F by employing 2 as a mild selenide transfer reagent. During the formation of C-Se bonds through the cleavage of C-F bonds, the potential by-product NHC ⋅ BH F undergoes ring expansion of the NHC, leading to the formation of the six-membered diaazafluoroborinane (7).