PUB - Publikationen an der Universität Bielefeld

A series of differently substituted 2,3-dihydro-1H-1,3,2-diazaboroles has been prepared by various methods. 1,3-Di-tert-butyl-2-trimethylsilylmethyl-1H-1,3,2-diazaborole (7), 2-isobutyl-1,3-bis(1-cyclohexylethyl)-1H-1,3,2-diazaborole (8), 1,3-bis-(1-cyclohexylethyl)-2-trimethylsilylmethyl-1H-1,3,2-diazaborole (9) 1,3-bis(1-methyl-1-phenyl-propyl)-2-trimethylsilylmethyl-1H-1,3,2-diazab orole (10) and 2-bromo-1,3-bis(1-methyl-1-phenyl-propyl)1 1H-1,3,2-diazabo role (11) were formed by reaction of the corresponding 1.4-diazabutadienes with the boranes Me3SiCH2BBr2, iBuBBr(2) and BBr3 followed by reduction of the resulting borolium salts [(RN)-N-1=CH-CH=N(R-1)(BRBr)-Br-2]Br [R-1 = tBu, Me(cHex)CH, [Me(Et)Ph]C; R-2 = Me3SiCH2, iBu, Br] with sodium amalgam. Treatment of 11 and 12 with silver cyanide afforded the 2-cyano-1,3,2-diazaboroles 13 and 14. An alternative route to compound 8 is based on the alkylation of 2-bromo-1,3,2-diazaborole 12 with isobutyllithium. Equimolar amounts of 13 and isobutyllithium give rise to the formation of 15. The new compounds were characterized by H-1-, C-13-, B-11-NMR, IR and mass spectra. The molecular structures of 7 and meso-10 were confirmed by x-ray structural analysis.