Reactions of the perfluoroarylboranes RB(C6F5)2 (R = C6F5, Ph, Cl, OC6F5) with Me3SiCH(N2), (C6F5)CH(N2) or Ph2C(N2) yield (C6F5)2B(Me3SiCH(C6F5)) 1, (C6F5)B(Me3SiCH(C6F5))22, (C6F5)B(Me3SiCH(C6F5))(Me3SiCH(C6H5)) 3, (C6F5)2B(CH(C6F5)2) 4, ClB(C6F5)(Ph2C(C6F5)) 5 and (C6F5O)B(C6F5)(Me3SiCH(C6F5)) 6 as a result of single or double insertion of a Me3SiCH, C6F5CH or Ph2C fragment into a B–C bond of the respective borane. Reactions of one or two equivalents of ethyl α-diazomethylacetate with B(C6F5)3 yielded (Me)(C6F5)(CC)(OC2H5)(OB(C6F5)2) 8 and [(Me)(C6F5)(CC)(OC2H5)]2(O2B(C6F5)) 9, in addition to the corresponding pyridine adducts (Me)(C6F5)(CC)(OC2H5)(OB(C6F5)2)(py) 10 and [(Me)(C6F5)(CC)(OC2H5)]2(O2B(C6F5))(py) 11. Similarly, reaction of α-diazomethylacetate with BPh3 yielded analogous products of borane reorganization, (Me)(C6H5)(CC)(OC2H5)(OBPh2) 12 and was isolated as a mixture of E and Z-isomers whereas BPh3 reacts with Me3SiCH(N2) and pyridine yielding (py)B(Ph2(Me3SiCH(Ph)) 7. Reactions of Ph2C(N2) with RB(OH)2 (R = C6F5, p-F-C6H4, C6H5) yielded cyclic boroxines of the form [Ph2C(R)BO]3 (R = C6F513, p-FC6H414, C6H515) while reactions of the boronate esters (C6H4O2)BR (R = C6F5, p-F-C6H4) with three or five equivalents of Me3SiCH(N2) yielded (C6H4O2)B(Me3SiCH(Ar)) (Ar = C6F516, p-F-C6H417) and [(Py)B(C6H4O2)(Me3SiCH(Ar))] (Ar = C6F518, p-F-C6H4, 19) upon complexation with pyridine. Reaction of HBCat and ClBCat with Ph2C(N2) yielded the products of B–H and B–Cl bond derivatization (C6H4O2)B(Ph2CR) (R = H 20, Cl 21), while the triethylphosphine oxide adduct (Et3PO)B(C6H4O2)(CPh2Cl) 22, is readily isolable.