Access to NHC–Boryl Mono‐ and Bis‐Selenide and Utility as Mild Selenium Transfer Reagent Including to the C−F Bond

Abstract Reactions of 5‐SIDipp ⋅ BH 3 (5‐SIDipp=1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐ylidene) ( 1 ) with diphenyldiselenide provide access to 5‐SIDipp–boryl mono‐ (5‐SIDipp ⋅ BH 2 SePh) ( 2 ) and bis‐selenide (5‐SIDipp ⋅ BH(SePh) 2 ) ( 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 2 )−F bonds of C 5 F 5 N and C 6 F 5 CF 3 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 6 F 6 could undergo complete defluoroselenation under harsh conditions, we successfully achieved partial defluorination of C 6 F 6 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 2 F undergoes ring expansion of the NHC, leading to the formation of the six‐membered diaazafluoroborinane ( 7 ).