Catalytic Hunsdiecker Reaction and One-Pot Catalytic Hunsdiecker–Heck Strategy: Synthesis of α,β-Unsaturated Aromatic Halides, α-(Dihalomethyl)benzenemethanols, 5-Aryl-2,4-pentadienoic acids, Dienoates and Dienamides
作者:Dinabandhu Naskar、Sujit Roy
DOI:10.1016/s0040-4020(99)01035-2
日期:2000.3
The reaction of α,β-unsaturated aromatic (or heteroaromatic) carboxylic acids with N-halosuccinimides (1 equiv.) and catalytic tetrabutylammonium trifluoroacetate (0.2 equiv.) in dichloroethane results in facile halodecarboxylation affording the corresponding (E)-halides in good to excellent yields. A similar reaction, but with 2 equiv. of N-halosuccinimides in acetonitrile-water (1:1 v/v) results
α,β-不饱和芳族(或杂芳族)羧酸与N-卤代琥珀酰亚胺(1当量)和催化四丁基三氟乙酸铵(0.2当量)在二氯乙烷中的反应导致容易的卤代羧化,从而得到相应的(E)-卤化物优异的产量。类似的反应,但具有2当量。的N在乙腈-水中(1-1:1 v / v)中的-卤代琥珀酰亚胺导致相应的α-(二卤代甲基)苯甲醇的排他性形成。此外,已开发出一种结合了Hunsdiecker催化反应(在二氯乙烷中使用三氟乙酸四丁基铵)和Heck偶联(使用乙酸钯/三乙胺/三苯基锑/二氯乙烷)的一锅法,用于合成5-芳基-2,4-戊二烯酸,酯和酰胺,产率中等至良好。通过上述途径合成了天然产物胡椒碱和哌瓜胺。机理和理论研究(通过AM1计算)对当前的卤代羧化反应的机理提供了有用的见解,表明离子途径涉及卤离子跨碳-碳双键的攻击,