C-乙氧基羰基N-芳基nitrilimines的环加成和它们的C-乙酰类似物4到α,β-不饱和的酮,得到主要的5-酰基-4-芳基-2-吡唑啉衍生物和分别。所述cycloadducts的结构和通过光谱(支持的13 C NMR,1 H NMR和IR)和分析数据。Tewari和Parihar关于这些反应的区域化学的结论无法维持。
Nuclear magnetic resonance spectroscopy and the structures of the regioisomeric products of the cycloaddition of C-ethoxycarbonyl-N-arylnitrilimines to α,β-unsaturated ketones
摘要:
H-1 NMR chemical shifts were used to assign the structures of the regioisomeric products obtained from the reactions of C-ethoxycarbonyl-N-arylnitrilimines 2A-E to alpha,beta-unsaturated ketones 3a-j. The assignments were based on the large observed difference between chemical shifts of the H-4 and H-5 of the 2-pyrazoline ring residue. Values of 1.29 +/- 0.06 and 0.34 +/- 0.03 ppm were found for DELTA-delta-4,5 for the 5-aroyl- and 4-aroyl-2-pyrazoline regioisomers 4 and 5, respectively. The regioselectivity in the studied cycloaddition reactions is interpreted in terms of FMO method.