Organic & biomolecular chemistry

Formation of dibenzofurans by flash vacuum pyrolysis of aryl 2-(allyloxy) benzoates and related reactions

M Black, JIG Cadogan, H McNab

Index: Black, Michael; Cadogan; McNab, Hamish Organic and Biomolecular Chemistry, 2010 , vol. 8, # 13 p. 2961 - 2967

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Citation Number: 12

Abstract

Flash vacuum pyrolysis (FVP) of aryl 2-(allyloxy) benzoates 5 and of the corresponding aryl 2-(allylthio) benzoates 6 at 650° C, gives dibenzofurans 19 and dibenzothiophenes 20, respectively. The mechanism involves generation of phenoxyl (or thiophenoxyl) radicals by homolysis of the O-allyl (or S-allyl) bond, followed by ipso attack at the ester group, loss of CO2 and cyclisation of the resulting aryl radical. Synthetically, the procedure works well ...