Detection of Claisen Rearrangement Occurring in Allyl Phenyl Ether by in situ GC/MS

We report here a new strategy for revealing the Claisen rearrangement of allyl phenyl ether occurring in the gas phase by in situ GC/MS technique. The Claisen rearrangement has been observed when allyl phenyl ether passed through the capillary column at certain temperatures. The relative proportion of rearrangement products is dependent on the temperature of the capillary column and the substituents on the phenyl ring.

Fluoroalcohol-mediated reductive iodonio-Claisen rearrangement： Synthesis of complex ortho-substituted-allyl iodoarenes

Reductive iodonio-Claisen rearrangement （RICR） involving 23-iodanes and allyl or substituted-allyl silanes in fluoroalcohols, such as 1,1,1,3,3,3-hexafluoroi- sopropanol （HFIP） and 2,2,2-trifluoroethanol （TFE）, was studied for the synthesis of complex ortho-allyl or substituted-allyl iodoarenes. In comparison to the pre- viously reported condition involving boron trifluoride diethyl etherate, the RICR mediated by fluoroalcohols was found to proceed more effectively. The resulting complex ortho-allyl iodoarenes are useful synthetic intermediates and can be readily converted to various heterocyclic compounds.

Rapid formation of β-allyl substituted isotetronic acid derivatives via Claisen rearrangement using a microfludic device

The thermal Claisen rearrangement of O-allyl substituted isotetronic acids 1 was successfully carried out within a glass microreactor operated with temperature at 150℃and a flow rate of 1 mL/h.The strategy provides an efficient alternative way toβ-allyl substituted isotetronic acid derivatives 2 in high yields with much accelerated reaction speed.

Highly Stereoselective Synthesis of (E, E)-3,7-Dimethyl-2,6-decadiene-1,10-diol

A total synthesis of (E,E)-3,7-dimethyl-2,6-decadiene-1,10-diol, using 1,3-transformation of 2, 3-epoxy alcohol and Claisen rearrangement of allyl vinyl ether as key steps, is described.

Synthesis of Novel Flavanone Derivatives and Their Anti Staphylococcus aureus Evaluation

The authors synthesized two novel flavanones bearing iso-pentenyl side chain and evaluated their anti Staphylococcus aureus（S.aureus） activity.The target compounds 7a[2-5＇-（l＂,2＂-dimethylallyl）-2＇-methoxy-4＇,5,7-tetrahydroxyflavanone] and 7b[2-5＇-（l＂,2＂-dimethylallyl）-3＇-methoxy-4＇,5,7-tetrahydroxyflavanone] were synthesized respectively through total four steps starting from 2,4,6-trihydroxy acetophenone（3） and the corresponding iso-pentenyl substituted benzaldehyde（1）,in which the 1,2-dimethyl-2-propenyl group had been introduced previously via abnormal Claisen rearrangement.The bioactivities of the two flavanones against S.aureus strains ATCC 25923,29213,and MRSA 252 were evaluated,showing the same minimum inhibitory concentration（MIC） value of 16 μg/mL.

Synthesis and Activity Evaluation of Novel Prenylated Flavonoids as Antiproliferative Agents

Twenty prenylated flavonoids 1-20 were synthesized by glycoside hydrolysis, dehydrogenation, selective O-methylation, O-prenylation and Claisen rearrangement reaction, from abundant and inexpensive natural flavonoids naringin, hespiredin, quercetin and myricetin. Among them, 1-7, 10-15 and 17-20 are novel compounds, the natural product 3,3＇,4＇,7-tetramethoxy-8-prenyl-5-hydroxy flavonoid（16） was synthesized in a high yield. Their antiprolirative activities were evaluated in vitro on a panel of three human cancer cell lines（HeLa, HCC1954 and SK-OV-3）. The results show that most of the target compounds displayed moderate to potent antiprolirative activities against the three cancer cells with half maximal inhibitory concentration（ICs0） values from 0.49 μmol/L to 95.07 μmol/L. Among them, 3′,4′,7-trimethoxyl-5-hydroxyl-8-prenyl flavonoid（12） exhibited the strongest antiprolirative activity against the three cancer cells mentioned above with IC50 values of 0.91-7.08 μmol/L. 3′,7-Dimethoxy-5-O- prenyl flavone（6） and 3′,4′,7-trimethoxy-5-O-prenyl flavone（10） showed selective antiproliferative activity against HCC1954 cells with TC50 value of 0 49 and 5 .32μmol/L, respectively.

Synthesis of[3,3'-Di-sec-butyl-4'-(2-dimethylaminoethoxy)-biphenyl-4-yl-oxy]acetic Acid

A modified synthetic route of[3,3'-di-sec-butyl-4'-(2-dimethylaminoethoxy)biphenyl-4-yloxy]acetic acid(1)with high total yield of 44%from biphenyl-4,4'-diol(2)is described.