TY  - JOUR
A1  - Thiess, Torsten
A1  - Ernst, Moritz
A1  - Kupfer, Thomas
A1  - Braunschweig, Holger
T1  - Facile Access to Substituted 1,4‐Diaza‐2,3‐Diborinines
JF  - Chemistry – A European Journal
N2  - Several bis(dimethylamino)‐substituted 1,4‐diaza‐2,3‐diborinines (DADBs) were synthesized with variable substituents at the backbone nitrogen atoms. By reaction with HCl or BX\(_{3}\) (X=Br, I), these species were successfully converted into their synthetically more useful halide congeners. The high versatility of the generated B−X bonds in further functionalization reactions at the boron centers was demonstrated by means of salt elimination (MeLi) and commutation (NMe\(_{2}\) DADBs) reactions, thus making the DADB system a general structural motif in diborane(4) chemistry. A total of 18 DADB derivatives were characterized in the solid state by X‐ray diffraction, revealing a strong dependence of the heterocyclic bonding parameters from the exocyclic substitution pattern at boron. According to our experiments towards the realization of a Dipp‐substituted, sterically encumbered DADB, the mechanism of DADB formation proceeds via a transient four‐membered azadiboretidine intermediate that subsequently undergoes ring expansion to afford the six‐membered DADB heterocycle.
KW  - azadiboretidines
KW  - B,N-heterocycles
KW  - diazadiborinines
KW  - diboranes
KW  - ring expansion
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214650
VL  - 26
IS  - 13
SP  - 2967
EP  - 2972
ER  - 
TY  - INPR
A1  - Arrowsmith, Merle
A1  - Böhnke, Julian
A1  - Braunschweig, Holger
A1  - Celik, Mehmet Ali
T1  - Reactivity of a Dihydrodiborene with CO: Coordination, Insertion, Cleavage and Spontaneous Cyclic Alkyne Formation
T2  - Angewandte Chemie, International Edition
N2  - Under a CO atmosphere the dihydrodiborene [(cAAC)HB=BH(cAAC)] underwent coordination of CO concomitant with reversible hydrogen migration from boron to the carbene carbon atom, as well as reversible CO insertion into the B=B bond. Heating of the CO-adduct resulted in two unusual cAAC ring-expansion products, one presenting a B=C bond to a six-membered 1,2-azaborinane-3-ylidene, the other an unprecedented nine-membered cyclic alkyne resulting from reductive cleavage of CO and spontaneous C≡C triple bond formation.
KW  - CO activation
KW  - diborene
KW  - ring expansion
KW  - insertion
KW  - cyclic (alkyl)(amino)carbene
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-153318
N1  - This is the pre-peer reviewed version of the following article: Arrowsmith, M., Böhnke, J., Braunschweig, H. and Celik, M., Reactivity of a Dihydrodiborene with CO: Coordination, Insertion, Cleavage and Spontaneous Cyclic Alkyne Formation. Angew. Chem. Int. Ed. 2017, 129,14475 –14480. Accepted Author Manuscript. doi:10.1002/anie.201707907. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
ER  -