Methylation of amines and ketones with palladacycle precatalyst has been performed using methanol as an environmentally benign reagent. Various ketones and amines undergo methylation reaction to yield monomethylated amines or ketones in moderate to good isolated yields. Moreover, this protocol was tested for the chemoselective methylation of 4-aminobenzenesulfonamide. The scope of the reaction was
Enantioselective synthesis of α-bromo acid derivatives and bromohydrins † from tartrate derived bromoacetals
作者:Scott A. Boyes、Alan T. Hewson
DOI:10.1039/b002106g
日期:——
Bromination of the acetals 4 derived from aryl alkyl ketones, ArCOR, and (2R,3R)-tartaric acid results in bromoacetals 5 with 78–90% de. Hydrolysis of those compounds with Ar = 4-methoxyphenyl or 3-bromo-4-methoxyphenyl results, after recrystallisation, in α-bromoketones 8 with 66–98% ee which are shown to undergo the Baeyer–Villiger oxidation to α-bromoesters 9 with minimal racemisation. α-Bromoketone
palladacycles (1 and 2) were synthesized by the aromatic C–H bond activation of N/3-aryl ring. The application of these regioisomers as catalysts to enable the formation of α-alkylated ketones or quinolines with alcohols using a hydrogen borrowing process is evaluated. Experimental results reveal that palladacycle 2 is superior over palladacycle 1 to catalyze the reaction under similar reaction conditions
Solvent-Free CatalyticFriedel-Crafts Acylation of Aromatic Compounds with Carboxylic Acids by Using a Novel Heterogeneous Catalyst System:p-Toluenesulfonic Acid/Graphite
作者:Mona Hosseini Sarvari、Hashem Sharghi
DOI:10.1002/hlca.200590162
日期:2005.8
TsOH/graphite was found to be an effective catalyst system for the Friedel–Crafts acylation of aromatic compounds with carboxylic acids. Both aliphatic and aromatic carboxylic acids reacted smoothly under TsOH/graphite catalysis to afford the corresponding aromatic ketones in high yields. The graphite was easily recovered by simple extraction and could be reused without decrease of activity in the
Acylation of anisole with carboxylic acids catalyzed by tungsten oxide supported on titanium dioxide
作者:Kazu Okumura、Masaki Iida、Hajime Yamashita
DOI:10.1016/j.mcat.2019.110410
日期:2019.10
Friedel-Crafts (F-C) acylation of anisole with octanoic acid was carried out on tungstenoxide (WO3) supported on various types of oxidesupports. We have found that the highest activity was obtained when TiO2 was used as the support. WO3/TiO2 was found to be active in the acylation of anisole with carboxylic acids of varying alkyl chain lengths (C6–C10). It was possible to recycle the WO3/TiO2 catalyst
苯甲醚用辛酸的弗里德尔-克拉夫茨(FC)酰化反应是在负载在各种氧化物载体上的氧化钨(WO 3)上进行的。我们已经发现,当TiO 2用作载体时,获得了最高的活性。发现WO 3 / TiO 2在苯甲醚与烷基链长度不同的羧酸(C6-C10)的酰化中具有活性。可以将WO 3 / TiO 2催化剂循环多达5次而不会失活。催化剂的周转频率(TOF)与用于WO 3的载体的阳离子的电负性密切相关。当强碱性氧化物如CeO 2时如果将其用作载体,则WO 3的酸强度降低,而WO 3的强酸度保留在诸如TiO 2的弱碱性载体上。这解释了为什么发现WO 3 / TiO 2催化剂的酸强度和活性最高。催化性能的趋势与通过温度程序化的NH 3脱附测量的在不同载体上的WO 3酸强度的顺序一致。