Rearrangement of 5- O -prenyl flavones: a regioselective access to 6- C -(1,1-dimethylallyl)- and 8- C -(3,3-dimethylallyl)-flavones
摘要:
Regioselective control of the Claisen rearrangement of 7-MEM-5-prenyl chrysin was achieved by microwave irradiation. The nature of the products was influenced by the irradiation power and the type of solvent. Irradiation at 750 W in N,N-diethylaniline specifically yielded the 8-(3,3-dimethylallyl) para-rearranged product while refluxing in N,N-diethylbutylamine gave selective access to the 6-(1,1-dimethylallyl) ortho-rearranged compound. (C) 2001 Elsevier Science Ltd. All rights reserved.