Additional Cyclic Compounds Containing a B-N Skeleton

Three different B2N4 heterocycles, 56, 57, and 58, have been reported. The reaction of 56a (R = CH3) and 56b (R = CeH5) with CSg leads to five-membered rings containing a BgNgS and BN2CS heterocycle. This was explained by a pseudo-dipolar cycloaddition [24]. 

Selected structural data of 56b are a twisted six-membered ring with interplanar deviations of 11 ° phenyl groups twisted relative to the CBN2 plane by 43.9°. Bond distances r(BN) range between 140.6 and 141.7 pm, r(NN) between 143.7 and 144.5 pm [24]. 

57a (R = C2H5) results from the reaction of [-B(C2H5)-N(C4H9-f)-]2 with C2HsOOCN=N-COOC2H5 in hexane at room temperature. The mass spectrum and IR data are given. NMR data H, B and 37.6 ppm), [8]. 

59 was prepared from [-B(C4H9-f)-N(C4H9-f)-]2 and CHgOOCC COOCHa in hexane under reflux. The structure is sterically overcrowded, which leads to splitting of the NMR signals at room temperature. Mass spectral, NMR ( H, C), and IR data are reported (in CjDq at 

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