Deux types de participation ? lors de l'hydrolyse des diazoc�tones ?, ?-insatur�es par des acides aqueux et des superacides. L'ion oxo-5-norbornyle-2
作者:Roger Malherbe、Hans Dahn
DOI:10.1002/hlca.19740570822
日期:——
γ, δ-Unsaturated diazoketones undergo acid catalysed hydrolysis accompanied by cyclisation; the latter is favoured by suitable geometry (cyclopentenes) and by substitution by methyl groups. If both are present, rate enhancement by anchimeric assistance has been observed. Hydrolysis of 4-diazoacetyl-cyclopentene (1) yields a product mixture similar to that formed during solvolysis of 5-oxo-norbornyl-2-endo
γ,δ-不饱和重氮酮经酸催化水解并环化; 后者因合适的几何形状(环戊烯)和被甲基取代而受到青睐。如果两者均存在,则已观察到通过嵌合辅助的速率增加。4-重氮乙酰基-环戊烯(1)的水解产生类似于5-氧代-降冰片基-2-内溴代磺酸盐(23)的溶剂化期间形成的产物混合物,并且与外型异构体的产物混合物完全不同。用常见的中间体5-氧代-2-降冰片基碳鎓离子解释了结果。溶剂参与过渡态,即部分S N2字符,是由活化的熵,并通过一个附加的亲核试剂(BR的动作隐含- )。在超强酸中,发生不同类型的环化反应,涉及羰基氧和质子化的CC双键并形成四氢吡喃衍生物。