Heterocycles Containing Four-Coordinate Annular Boron

S Heterocycles Containing Four-Coordinate Annular Boron 

Heterocycles of type 27 are prepared by thioboration of benzyl cyanide with the corresponding diorganyl(thioorganyl)boranes upon heating the mixture from 100 to 130°C. Mass spectral, NMR ( H with 6 B = -4.7 ppm), and IR data are reported [18]. The species 28 is obtained by cycloaddition of phenylisonitrile to 2-di-n-butylborylaminopyridine [19]. 

Dialkyl(alkyl-A/-1H-tetrazol-5-ylalkan(or benzenecarbox)imidato)-boron compounds of type 29 have been prepared from 5-aminotetrazole, nitriles, R CN, and trialkylboranes, R3B, by heating the stirred mixture (containing an excess of R CN) to 120°C [20, 21]. The derivatives are characterized by mass spectral, IR, and UV data. An X-ray structure analysis was performed on 29f. The bicyclic skeleton of this compound is almost planar with some distortion about the boron atom [20]. 

The dialkyl(alkyl-A/-1H-1,2,4-triazol-3-ylbenzenecarboximidamidato)-boron compounds of type 30 are prepared in analogy to 29 from the corresponding trialkylboranes by reaction with 5-amino-1,2,4-triazole in refluxing xylene and treating the intermediate with a 3- to 5-fold excess of the corresponding aryl nitrile under reflux. The mass spectrum, the NMR spectrum, and IR data are given for the various species. The crystal and molecular structure of 30a has been determined by X-ray diffraction it resembles that of 29f [22]. 

Complexes of type 31 are obtained from R2B-SC4H9-n and A/-organyl-A/ -(1,3-thiazol-2-yl)-thioureas by thermal isomerization of the chelates formed in the first step of the reaction. The mass spectra, NMR, B NMR, and IR data are reported as well as their complexes with Ni and PdClg [23]. 

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