THERMAL BEHAVIOUR OF ARYL γ-HALOPROPARGYL ETHERS

Article abstract of DOI:10.1016/0040-4020(89)80058-4

A systematic study of the behaviour of aryl γ-halopropargyl ethers under thermal condition was undertaken.Aryl γ-bromopropargyl ethers 2 underwent unique transformation in N,N-diethylaniline (215 deg C, 6 h) giving rise to a mixture of products 3,4 and 5,whereas, under similar conditions aryl γ-chloropropargyl ethers 8, afforded 4-chlorochromenes, 9.A remarkable substituent and solvent effect has been observed in the thermolysis of these aryl γ-bromo and γ-chloropropargyl ethers, rendering this transformation as a method for the synthesis of a number of substituted 4-bromochromenes 3, 4-chlorochromenes 9 and chroman-4-ones 7.In contrast, solution thermolysis of aryl γ-iodopropargyl ether 11 afforded aryl propargyl ether 1 as the major product.