1099654-12-2Relevant academic research and scientific papers
Ionic Liquids with Multi-Active Sites Synergistically Catalyzed Metal-Free Transformation of Alcohols Using Dimethyl Carbonate as an Environmental Solvent
Li, Zengmin,Wen, Yating,Wang, Ning,Han, Feng,Li, Ying,Zhuang, Hongfeng,Miao, Chengxia
, p. 3819 - 3826 (2021)
One of the ultimate goals in organic synthesis is to develop metal-free, efficient and easily separable catalytic system for atom economic organic reactions in an environmental solvent. Direct substitution reaction of alcohols and hydrocarbon compounds is a significant and atom economic method for C?C bond formation. Herein, a metal-free and efficient catalytic system including recyclable pyridine-based ionic liquids with multiple active sites as the catalyst and dimethyl carbonate as the environmentally friendly solvent was developed for atom economic C3 substitution of 4-hydroxycoumarins with alcohols. Primary aromatic alcohols, secondary aliphatic and aromatic alcohols were suitable for the reaction, providing up to 99 % yield. The catalytic system could be easily scaled up to gram-scale with nearly quantitative yield. Coumatetralyl as commercial rodenticide could be prepared directly from commercially available 4-hydroxycoumarin and 1,2,3,4-tetrahydronaphthalen-1-ol. Racemic product derived from the reaction of (R)-1-phenylethanol and 4-hydroxycoumarin indicated the reaction was achieved through an SN1 pathway. The comparison of the activities and acidities of the ionic liquids demonstrated that there was no directly relationship between them. Control experiments showed that the reaction probably proceeded via carbocation, ether intermediate and synergistically promoted effect of hydrogen bonding between the ionic liquid with multi-active sites and substrates.
An efficient greener copper triflate-catalyzed C-3 benzylation of 4-hydroxycoumarin and some active methylene compounds
Ganguly, Nemai C.,Chandra, Sumanta
, p. 547 - 555 (2012/10/29)
4-Hydroxycoumarin has been directly benzylated at C-3 position with a good number of secondary benzylic alcohols using copper triflate catalyst (2 mol%) in toluene under reflux. The protocol provides an efficient, expedient and atom-economic access to warfarin and coumatetralyl analogues with potential anticoagulant activity. The protocol has been extended to benzylation of 4-hydroxy-1-methylquinolin-2(1H)-1-one, N-methylbarbiturate and some other active methylene compounds with remarkable success.
