First B-Organyloxy-Substituted Iminoboranes:  Preparation, Stabilization, and Reactivity

Abstract

The amino(halo)(organyloxy)boranes ROB(X)N(H)R‘ (R = 2,6- t Bu 2 C 6 H 3, X = Cl, R‘ = t Bu ( 7 ), SiMe 3 ( 8 ), 2,6- i Pr 2 C 6 H 3 ( 9 ), 2,4,6-Me 3 C 6 H 2 ( 10 ), 2,4,6- t Bu 3 C 6 H 2 ( 11 ); R = 2,6-C 6 H 5 ) 2 C 6 H 3, X = Cl, R‘ = t Bu ( 12 ); R = 2,6- t Bu 2 C 6 H 3, X = F, R‘ = t Bu ( 13 ), 2,6- i Pr 2 C 6 H 3 ( 14 ); R = t Bu 3 C, X = F, R‘ = i Pr ( 15 ), t Bu ( 16 ), SiMe 3 ( 17 )) were dehydrohalogenated with tert -butyllithium at low temperature. The reaction involved the intermediate formation of an aryloxy(imino)borane in the case of 7, 9, 11, and 12 . The diazadiboretidines [ROB NR‘] 2 (R = 2,6- t Bu 2 C 6 H 3, R‘ = t Bu ( 18 ), SiMe 3 ( 19 ), 2,6- i Pr 2 C 6 H 3 ( 20 ), 2,4,6-Me 3 C 6 H 2 ( 21 ); R = t Bu 3 C, R‘ = i Pr ( 22 ), SiMe 3 ( 23 )) were isolated as the ultimate products of the reactions. The aryloxy(imino)borane 2,6- t Bu 2 C 6 H 3 −O−B⋮N- t Bu (derived from 7 ) was reacted with BEt 3 and Me 3 SiN 3 to give the corresponding 1,2-addition products across the (B≡N) triple bond ( 25 and 26, respectively). The compounds were characterized by NMR spectroscopy ( 1 H, 11 B, 13 C, 29 Si), MS (EI and FI), and elemental analyses. X-ray structure determinations are presented for 18, 22, and 26 .