Abstract
2,5-Bis(chloro-2,2,6,6-tetramethylpiperidinoboryl)thiophene (1) and 2,5-bis(chloro-diisopropylaminoboryl) pyrrol (4) react with two equivalents of 2-lithiothiophenide to yield the corresponding 2,5-diborylheteroarenes (2,5) in which two boryl groups connect three heteroarenes. After lithiation of the terminal thiophenes of both compounds in 5,5'-position their reactions with the diborylthiophene 1 as well as with diborylpyrrol 4, lead to tetraboraporphyrinogenes (3, 6), the latter being the first tetraboratetraazaporphyrinogene. By silicon / boron exchange of 1-trimethylsilylimidazol with the 2,5-diborylpyrrol 4 the 2,5-bis(imidazolyldiisopropylamino- boryl)pyrrol 7 is formed, which reacts with BH3 and BEt3 to give the N-borane adducts of 7. The spectroscopic data and four X-ray structure analyses are reported.