Efficient and Selective Formation of Phenylacetic Acids from Diketene

在Ni催化剂存在下，双乙烯酮、炔和Me 2 Zn三种组分顺利联合收割机，以优异的产率提供3-亚甲基-4-己烯酸。 此外，在类似的催化条件下，Et 2Al（OEt）促进与双烯酮和2当量的炔的[2+2+2]环加成反应，得到取代的苯乙酸。 更有趣的是，在Et_2Al（OEt）和膦配体存在下，双乙烯酮和2当量的炔通过[2+2+1+1]环加成反应，并伴随双乙烯酮的亚甲基C=C双键的断裂反应，得到了对称的苯乙酸，这是双乙烯酮选择性生成不饱和羧酸和苯乙酸的第一个实例。 该反应在合成类异戊二烯酸和非甾体抗炎药等具有生理活性的化合物方面有着广阔的应用前景。

In the presence of Ni catalyst, three components of diketene, alkyne, and Me2Zn combine smoothly to provide 3-methylene-4-hexenoic acids in excellent yields. Furthermore, under similar catalytic conditions, Et2Al(OEt) promotes [2+2+2] cycloaddition reactions with diketene and 2 equivalents of alkyne to give rise to the substituted phenylacetic acids. More interestingly, in the presence of Et2Al(OEt) and phosphine ligand, symmetrical phenyl acetic acids are constructed via the formal [2+2+1+1] cycloaddition reactions with diketene and 2 equivalents of alkyne accompanying the cleavage reaction of methylene C=C double bond of diketene.This is the first example of the selective formation of unsaturated carboxylic acids and phenylacetic acids from diketene involving oxanickelacycles. The reaction presented here might be a powerful tool in the expedient synthesis of the physiologically active molecules, such as isoprenoid acids and non-steroidal anti-inflammatory drugs (NSAIDs).