120610-80-2Relevant academic research and scientific papers
Structural Requirements for the Formation of the B2ElVIN2 Heterocycles
Yalpani, Mohamed,Boese, Roland,Koester, Roland
, p. 1231 - 1236 (2007/10/02)
The reactions of the bis(diorganoboryl) chalcogenides (R2B)2ElVI VI = O (9); R2 = 1,5-C8H14 (1, ElVI = O), (2, ElVI = S)> with 3-methyl-, 3,5-dimethyl-, 3-methyl-5-phenyl-, 3,5-diphenyl-, and 3,5-di-tert-butylpyrazole have been investigated. mPz reacts with 2 to form the heterocycle m5, which due to the interaction of the methyl substituent with the carbon skeleton of 2 is unstable and readily rearranges to the novel heterocycle 7 (X-ray analysis) when dissolved in toluene at room temperature.In contrast the analogues m4 (El = O), formed from mPz and 1, is stable even when heated at 100 deg C.The reaction of 1 with m2Pz and mpPz does not produce stable heterocycles of the type 4, instead the 1:1 adducts m2Pz-1 and mpPz-1 are formed in which the pyrazole fluctuates between the two boron atoms of 1.The diboryl oxide 1 showed only weak interactions with mpPz and none with p2Pz and (tb)2Pz.With 9 the pyrazoles m2Pz, mpPz, and p2Pz form readily the corresponding heterocycles 10, however no reaction was observed with (tb)2Pz (1H-, 11B-,13C-NMR). - Key Words: Bis(diorganoboryl) chalcogenides / Pyrazoles / N-Base-Organoboron adducts / Molecular rearrangement / Fluctuation
