134152-50-4Relevant academic research and scientific papers
Eight-Membered BN Rings (RBNR')4 from Four-Membered BN Rings (RBNtBu)2 by an Exchange NtBu/NR'
Thiele, Bjoern,Schreyer, Peter,Englert, Ulli,Paetzold, Peter,Boese, Roland,Wrackmeyer, Bernd
, p. 2209 - 2216 (2007/10/02)
Reactions of the four-membered BN ring compounds (RBNtBu)2 (1a-e): R = Me, Et, iPr, iBu, Pr) with azides R'N3 (R' = PhCH2, Pr, iBu, Ph) and with the nitrone PhHCN(Me)O are studied.The five-membered ring (Me)BN(tBu)-N=N-(PhCH2)N> (2a) is formed from the four-membered ring 1a and PhCH2N3 in the ratio 1:2.An exchange of NtBu for N'R with elimination of tBuN3 is observed, however, in the reaction of the ring compounds 1b-d with R'N3.Instead of four-membeed BN rings, the six-membered BN ring (RBNR')3 (3a: R/R' = Et/PhCH2) and the eight-membered BN rings (RBNR')4 (4a-h: R/R' = iPr/PhCH2, iBu/PhCH2, iPr/Pr, iBu/Pr, iPr/iBu, iBu/iBu, Et/Ph, iBu/Ph) are formed, respectively.The NMR spectra reveal diasterotopic methylene protons (Et, Pr, iBu, PhCH2) and methyl groups (iPr, iBu) and thus elucidate the tub-like structure of the eight-membered rings. 3a and 4a crystallize in the space group P21/c.The reaction of the four-membered rings 1c-e with the nitrone gives five-membered rings (R)BN(tBu)B(R)N(Me)-O> (5c-e).Both of the reactions of the four-membered rings with azides and with the nitrone can be rationalized in terms of a similar sequence of reaction steps. Key Words: Tetrazatetraborocanes / Boron-nitrogen ring compounds / Cycloadditions
