Covalently Bound Benzyl Ligand Promotes Selective Palladium‐Catalyzed Oxidative Esterification of Aldehydes with Alcohols

Abstract

It's a benzyl kind of magic: In the title reaction proceeding with benzyl chloride as the oxidant, the benzyl group serves as a carbon ligand, thus having an η3‐coordination effect on palladium (see scheme). A variety of aldehydes and alcohols were selectively converted into the corresponding esters in good to excellent yields.

The Preparation of a Highly Efficient Ag3PO4/Ag/Bi2O2CO3 Photo-Catalyst and the Study of Its Photo-Catalytic Organic Synthesis Reaction Driven by Visible Light

“…However, myriads of by-products are generated as part of these synthetic processes, which both wastes resources and creates environmental pollution [4][5][6]. Recently, precious metal catalysts supported on carriers (such as Ir [7,8], Cu [9,10], Pd [11], and Au [12]) have been applied in the above-mentioned synthetic processes. However, the reaction conditions have been severe, for example, equivalents of metal salts or metal oxides (such as KMnO 4 [13], MnO 2 [14] or KHSO 4 [15]) were added as oxidants, which created many by-products in the reaction, thus making the utilization ratio of the raw material unfavorable [16][17][18][19][20].…”

Generally applicable and efficient esterification of aldehydes with alcohols catalyzed by cyclopalladated ferrocenylimine

“…Further efforts have been devoted to the direct synthesis of esters from the oxidative esterification of aldehydes with alcohols, in which stoichiometric amounts of metal salts like KHSO 5 , oxone or MnO 2 have to be employed as oxidants . Very recently, in the development of both selective palladium‐catalyzed aldehyde formation and oxidative esterification, significant progress has been achieved by several groups, such as those of Lei, Beller and others . Although several methods have been reported for the direct preparation of aldehydes to esters, those methods usually require a high loading catalyst, extremes of temperature, long reaction times, inert atmosphere, photochemical conditions, poisonous and polluting reagents, mediators or co‐catalysts.…”

“…[6] Very recently, in the development of both selective palladiumcatalyzed aldehyde formation and oxidative esterification, significant progress has been achieved by several groups, such as those of Lei, Beller and others. [7,8] Although several methods have been reported for the direct preparation of aldehydes to esters, those methods usually require a high loading catalyst, extremes of temperature, long reaction times, inert atmosphere, photochemical conditions, poisonous and polluting reagents, mediators or co-catalysts. Some of these reaction conditions are also unsatisfactory for the specific oxidation of aldehydes containing deactivated, hindered and double-bond-containing substrates, resulting in over-oxidation and undesirable products, proceeding non-selectively, and affording the desired product in poor to moderate yields.…”

Recent Advances in Oxidative Coupling Reactions

“…在我们实验室开发 的金属试剂作为亲核试剂的氧化羰基化反应的基础上 [8,11] , 2011 年, 我们报道了杂环化合物作为亲核试剂的 氧化羰基化反应(Eqs. 14～16) [47] 根据文献相关报道, 我们了解到 ArCOPdAr 物种的 还原消除步骤是个容易进行的过程 [55] , 因此推断: 第二 [66] 报道了共价偶联配体苄基促进的钯催化的醛与醇的选 择性氧化酯化反应(Eq. 19), 发现氧化剂可以很好的控 制该类反应的选择性 [67] .…”