01752nas a2200265   4500008004100000022001400041245016300055210006900218260007300287300001200360490000700372520077300379653001401152653002301166653002101189653001301210653001701223653001501240653001401255100001901269700002301288700002501311700002301336856012701359       2008                        eng d  a1350-417700aEfficient synthesis of 1,8-dioxo-octahydro-xanthene derivatives promoted by a room temperature ionic liquid at ambient conditions under ultrasound irradiation0 aEfficient synthesis of 18dioxooctahydroxanthene derivatives prom  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAPR  a548-5530 v153 a<p>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.</p>10aaldehydes10aambient conditions10aBronsted acidity10adimedone10aIonic liquid10aUltrasound10aXanthenes1 aVenkatesan, K.1 aPujari, Suresh, S.1 aLahoti, Rajgopal, J.1 aSrinivasan, K., V.  uhttps://library.ncl.res.in/content/efficient-synthesis-18-dioxo-octahydro-xanthene-derivatives-promoted-room-temperature-0