Rhodium-Catalyzed Ketone Methylation Using Methanol Under Mild Conditions: Formation of α-Branched Products
作者:Louis K. M. Chan、Darren L. Poole、Di Shen、Mark P. Healy、Timothy J. Donohoe
DOI:10.1002/anie.201307950
日期:2014.1.13
The rhodium‐catalyzed methylation of ketones has been accomplished using methanol as the methylating agent and the hydrogen‐borrowing method. The sequence is notable for the relatively low temperatures that are required and for the ability of the reaction system to form α‐branched products with ease. Doubly alkylated ketones can be prepared from methyl ketones and two different alcohols by using a
Radical Carbonylation under Low
<scp>CO</scp>
Pressure: Synthesis of Esters from Activated Alkylamines at Transition
<scp>Metal‐Free</scp>
Conditions
作者:Fengqian Zhao、Han‐Jun Ai、Xiao‐Feng Wu
DOI:10.1002/cjoc.202000624
日期:2021.4
HighCOpressure (> 40 bar) is usually needed in radical carbonylation reactions in the absence of metal catalyst. In this communication, we developed a transition‐metal‐free radical carbonylation of activated alkylamines with phenols and alcohols under low COpressure (1—6 bar). Various esters were obtained in moderate to excellent yields under simple reaction conditions with good functional group
undivided cell, of Ph3P in the presence of a carboxylic acid in CH2Cl2 containing 2,6-lutidinium perchlorate as the supporting electrolyte was shown to generate the corresponding acyloxyphosphonium ion, Ph3P+-OCOR, which was converted in situ to esters, amides, and β-lactams under mild conditions.
结果表明,在羧酸存在下的CH 2 Cl 2中,含高氯酸2,6-lut啶鎓作为辅助电解质的PH 3 P在不分隔的电池中恒流电解会生成相应的酰氧基phosph离子Ph 3 P + -OCOR,在温和条件下原位转化为酯,酰胺和β-内酰胺。
Hafnium inspired activation of highly hindered anhydrides in the acylation of alcohols and polyols
作者:Enoch Mensah、Aaron Day、Raven Thomas
DOI:10.1016/j.tetlet.2018.02.009
日期:2018.3
A novel and highlyefficient method for activating highly hindered acid anhydrides towards the acylation of alcohols and carbohydrate-derived polyols has been developed. This new method relies on the capacity of the hafnium triflate catalyst Hf(OTf)2 to activate highly hindered acid anhydrides, and to direct the acylation reaction. This new acylation protocol is mild and proceed at room temperature
In the presence of a catalytic amount of Lewis acid, various carboxylic esters or S-phenyl carbothioates are prepared in excellent yields by the respective reactions of equimolar amounts of silyl carboxylates and alkyl silyl ethers or phenyl silyl sulfides with 4-trifluoromethylbenzoic anhydride.