A NEW METHOD FOR THE GENERATION OF SILAHE TEROCYCLES VIA [4-CYCLOADDITION REACTION IN THE SYSTEM HETEROBUTADIENE(1])HSICL3/NR3/

The reaction of trichlorosilane with tert. amines provides the anion S iCl3- (Benkeser type system). This system can be used as a simple acce ssible SiCl2 synthon in certain cases. Thus [4 + 1]-cycloadditions of diazabutadienes in the system HSiCl3/NR3 lead to silacyclopentene deri vatives. The reaction of 1,3-diaza-1,3-dienes with equimolar amounts o f DBU and HSiCl3 in THF gives the 1,4-diazasila-cyclopentene (CF3)(2)C -N=C(Ph)-N(Bu-t)-SiCl2 (2a) derivative only in one case [6], whereas i n other cases hydrosilylation products are obtained. In (CF3)(2)CH-N=C (Ph)-N(Bu-t)SiCl2F (3a), which is obtained from (2a) with wet toluene, the amidinate is bidentate and thus coordinating in a chelating fashi on to the five-coordinate silicon atom. 1,4-diaza-1,3-dienes (DAD) giv e the [4 + 1]-cycloaddition products in all cases. Product distributio n and yield are strongly influenced by the substituents, the nature of the solvent and the reaction conditions. All compounds have been char acterized by NMR and mass spectroscopy. In five cases, the results of crystal structure determinations by X-ray diffraction are reported.