Radical Scission of Symmetrical 1,4-Dicarbonyl Compounds: C−C Bond Cleavage with Titanium(IV) Enolate Formation and Related Reactions
作者:Theodor Agapie、Paula L. Diaconescu、Daniel J. Mindiola、Christopher C. Cummins
DOI:10.1021/om0107284
日期:2002.4.1
symmetrical 1,4-diketones (ArCOCH2)2 (Ar = p-Tol or p-MeOC6H4) in hydrocarbon solvents at ≤25 °C resulted in carbon−carbonbond cleavage with clean formation of titanium-bound enolates, 1-OC(CH2)Ar. Treatment of Ti(NRAr1)3 with esters or amides of succinic acid, under the same mild conditions, smoothly produced titanium(IV) compounds containing the corresponding amide or ester enolate moiety. The amide enolate
Ti(NRAr 1)3(1,R = C(CH 3)3,Ar 1 = 3,5-C 6 H 3 Me 2)与0.5当量的对称1,4-二酮(ArCOCH 2)2( Ar = p- Tol或p -MeOC 6 H 4)在≤25°C的烃溶剂中导致碳-碳键裂解,形成结合钛的烯醇化物1 -OC(CH 2)Ar。Ti(NRAr 1)3的处理在相同的温和条件下,用琥珀酸的酯或酰胺与含相应酰胺或酯烯酸酯部分的钛(IV)化合物平稳地合成。酰胺烯醇化物以苯甲醛的方式与苯甲醛缩合。借助计算方法可以解释所观察到的酰胺基-烯醇对酮与酮衍生的烯醇对醛醇缩合反应的差异。与Ti(NRAr 1)3反应时,对取代的苯乙酮可产生等量的烯醇盐和醇盐产物。在相似的实验条件下,苯乙酮本身可以定量地产生一种物种,该物种的拟议结构具有让人联想到Gomberg二聚体的特征。加热后,该中间体干净地分解为预期的烯醇化物和醇盐混合物。Ti(NRAr