Vitamins and antivitamins K: tautomerism of dicoumarol
作者:I. Chmielewska、J. Cieślak
DOI:10.1016/0040-4020(58)88012-6
日期:1958.1
Two isomeric dimethyl ethers of dicoumarol and derivatives substituted in the methylene group [formulae (XX) and (XXI)] were obtained. This result proves the tautomerism of dicoumarol and suggests for it the coumarin-chromone structure (XXIIa).
Studies on 4-Hydroxycoumarin. III. Dehydration of the Aldehyde Condensation Products<sup>1</sup>
作者:Charles F. Huebner、William R. Sullivan、Mark A. Stahmann、Karl Paul Link
DOI:10.1021/ja01252a009
日期:1943.12
Sulfated titania catalyzed water mediated efficient synthesis of dicoumarols—a green approach
作者:Bikash Karmakar、Anupam Nayak、Julie Banerji
DOI:10.1016/j.tetlet.2012.06.024
日期:2012.8
An efficient, mild, and environmental friendly method has been developed for the synthesis of dicoumarols in water over Lewis and Bronsted acid catalyst sulfated titania (TiO2/SO42-). The method involves the condensation of various aromatic and aliphatic aldehydes with 4-hydroxycoumarin. It affords the corresponding product in high yield with short reaction times employing a very low loading of catalyst. The catalyst was reused several times without significant change in activity. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.
Ionic liquid: an efficient and recyclable medium for the synthesis of octahydroquinazolinone and biscoumarin derivatives
作者:Jitender M. Khurana、Sanjay Kumar
DOI:10.1007/s00706-010-0306-4
日期:2010.5
A facile and environmentally benign procedure for the synthesis of octahydroquinazolinone and biscoumarin derivatives in ionic liquids is reported. Octahydroquinazolinones were synthesized in the presence of trimethylsilyl chloride (TMSCl) while the synthesis of biscoumarins required no additive. The ability to reuse the ionic liquid, the high yields, and ease of purification are the important features of this process.
Studies on 4-Hydroxycoumarins. II. The Condensation of Aldehydes with 4-Hydroxycoumarins<sup>1</sup>
作者:William R. Sullivan、Charles F. Huebner、Mark A. Stahmann、Karl Paul Link