Flash vacuum pyrolysis of aryl propargyl ethers

Flash vacuum pyrolysis (FVP) of aryl propargyl ether 9 produces 2-methylbenzofuran 21, 2H-chromene indanone 22 and benzocyclobutene 23. o-chloro- and bromo-aryl propargyl ethers 10 &11 resulted mainly in methylbenzofurans 25, 26 &29 and 2H-chromene derivative 27. On the other hand, FVP of arylpropargyl ethers with an active substituent at the ortho position of the aryl group 12-15 &20 has resulted in interesting, unexpected products. All products were analyzed, fully characterized, and identified. Mechanisms are proposed for most of these FVP reactions. [Display omitted] •FVP reaction for twelve aryl propargyl ethers were performed.•Reaction products were analyzed, characterized, and identified.•Non-ortho substituted aryl ethers chose Claisen-rearrangement leading to 2-indanones and benzocyclobutene.•An active function group at the ortho position interacts with carbene intermediates to form interesting unexpected products.