Arylation of diethyl malonate and ethyl cyanoacetate catalyzed by palladium/di-tert-butylneopentylphosphine
作者:Jeffrey G. Semmes、Stephanie L. Bevans、C. Haddon Mullins、Kevin H. Shaughnessy
DOI:10.1016/j.tetlet.2015.01.072
日期:2015.6
α-Arylated carbonyl derivatives are important structural motifs in many natural products and pharmaceutically active compounds. Although arylation of simple monocarbonyl compounds is a well-established methodology, metal-catalyzed arylation of β-dicarbonyl derivatives is significantly more challenging. The ability of β-dicarbonyl anions to bind to palladium in a κ2-O,O mode, rather than the κ1-C-bound
在许多天然产物和药物活性化合物中,α-芳基化羰基衍生物是重要的结构基序。尽管简单的单羰基化合物的芳基化是一种公认的方法,但金属催化的β-二羰基衍生物的芳基化更具挑战性。β二羰基的阴离子结合至钯在κ的能力2 - ø,ö模式,而不是κ 1 - c ^结合的模式键形成所需的,经常导致催化剂体系的失活。烯醇盐的C-结合形式可通过使用空间需求的配体来促进。在此,我们报告中指出,空间要求的二叔丁基丁基新戊基膦(DTBNpP)配体与Pd(dba)2结合为芳基溴化物和氯化物与丙二酸二乙酯的偶联提供了有效的催化剂。Pd / DTBNpP系统还催化芳基溴化物与氰基乙酸乙酯的偶联。
Enantioselective Synthesis of Chiral Cyclopent-2-enones by Nickel-Catalyzed Desymmetrization of Malonate Esters
enantioselective synthesis of highly functionalized chiral cyclopent-2-enones by the reaction of alkynyl malonate esters with arylboronic acids is described. These desymmetrizing arylative cyclizations are catalyzed by a chiral phosphinooxazoline/nickel complex, and cyclization is enabled by the reversible E/Z isomerization of alkenylnickel species. The general methodology is also applicable to the synthesis of
Copper-catalyzed C-C couplingreaction of aryl iodides with diethylmalonate in toluene at 90 °C gave arylated malonates using 5 mol% of CuI with hydrazone la as a ligand in good yields under an aerobic atmosphere. We also found Cul/hydrazone 1b in toluene to be an efficient catalytic system for C-O couplingreactions of aryl bromides with phenols to give aryl ethers in good yields at 110 °C under an
在 90°C 下,芳基碘化物与丙二酸二乙酯在甲苯中的铜催化 CC 偶联反应得到芳基化丙二酸酯,使用 5 mol% 的 CuI 和腙 1a 作为配体,在有氧气氛下以良好的收率。我们还发现甲苯中的 Cul/腙 1b 是一种有效的催化体系,用于芳基溴化物与苯酚的 CO 偶联反应,在 110 °C 有氧气氛下以良好的产率得到芳基醚。
Protonation and transformations of α-diazo-β-dicarbonyl compounds in superacids: generation of the strongest carbon-centered cationic electrophiles at the protonation of diazomalonates in Friedel–Crafts reactions
作者:Eugeniy T. Satumov、Jury J. Medvedev、Denis I. Nilov、Maria A. Sandzhieva、Irina A. Boyarskaya、Valerij A. Nikolaev、Aleksander V. Vasilyev
DOI:10.1016/j.tet.2016.06.051
日期:2016.8
Protonation of diazodiketones N2C(COR)2 in Brønsted superacids (TfOH, FSO3H, TfOH–SbF5) gives rise to stable and non-reactive O,O-diprotonated at carbonyl oxygens species N2C(C(OH+)R)2, which were studied by means of 1H and 13C NMR. Diazomalonates N2C(CO2Alk)2, contrary to diazodiketones, react with TfOH or HF, releasing nitrogen and producing triflates of oxymalonates TfOCH(CO2Alk)2 or fluoromalonates
Transition-metal-catalyzed enantioselective functionalization of acyl radicals has so far not been realized, probably due to their relatively high reactivity, which renders the chemo- and stereocontrol challenging. Herein, we describe Cu(I)-catalyzed enantioselective desymmetrizing C–O bond coupling of acyl radicals. This reaction is compatible with (hetero)aryl and alkyl aldehydes and, more importantly