@article { ISI:000254443900045, title = {Efficient synthesis of 1,8-dioxo-octahydro-xanthene derivatives promoted by a room temperature ionic liquid at ambient conditions under ultrasound irradiation}, journal = {Ultrasonics Sonochemistry}, volume = {15}, number = {4}, year = {2008}, month = {APR}, pages = {548-553}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The condensation reaction involving an aldehyde and diketone was efficiently promoted by the Ionic liquid, [Hbim]BF(4) (IL) as a reaction medium with methanol as co-solvent at ambient temperature under ultrasonic irradiation to afford the corresponding 1,8-dioxo-octahydroxantliene (xanthene) derivatives in excellent yields. The advantages of this method include among others the use of a recyclable, non-volatile ionic liquid, which promotes this protocol under ambient temperature without the requirement of ally added catalyst. The reaction times and yields are compared with p-TSA catalyzed synthesis of xanthenes under thermal conditions, which is also reported for the first time under our reaction conditions. (c) 2007 Elsevier B.V. All rights reserved.

}, keywords = {aldehydes, ambient conditions, Bronsted acidity, dimedone, Ionic liquid, Ultrasound, Xanthenes}, issn = {1350-4177}, doi = {10.1016/j.ultsonch.2007.06.001}, author = {Venkatesan, K. and Pujari, Suresh S. and Lahoti, Rajgopal J. and Srinivasan, K. V.} }