FROM AZOLE-BORANE ADDUCTS TO AZABOLES - MOLECULAR-STRUCTURE OF AN IMIDAZABOLE

Elimination of H2 from the imidazole-borane adduct 1 leads to a mixtur e of the imidazaboles 2 and 2'. The symmetrical isomer 2 (two H2BNC fr agments) is isolated in pure state and characterized by an X-ray struc ture analysis (monoclinic, space group P2(1)). 2-(Trimethylstannyl)thi azole (3a) and 1-methyl-5-(trimethylstannyl)-1,2,4-triazole (3b) react with triethylborane to form adducts 4 from which, in the presence of an excess of Et3B, tetraalkyltin is elimated to give the thiazabole Sa and the triazabole 5b, respectively. Multinuclear H-1-, B-11-, C-13-, N-14-, and Sn-119-NMR spectroscopy serve for following the reactions (compounds 3 to 5) and to characterize all final products.