Hh. Karsch et al., TRIFLUOROMETHYL-SUBSTITUTED GERMANIUM HET EROCYCLES VIA [4+1] CYCLOADDITION REACTIONS, Zeitschrift fur Naturforschung. B, A journal of chemical sciences, 50(2), 1995, pp. 289-293
Formation of partially fluorinated imidazoles 6 from 4,4-bis(trifluoro
methyl)-1,3-diazabuta-1,3-dienes 1 in the presence of low-valent metal
compounds is shown to proceed via a [4+1] cycloadduct in the case of
germanium(II)-chloride. The resulting germole 3 has been characterized
by X-ray analysis. The five-membered ring is planar and the germanium
atom adopts tetrahedral configuration.