Generation and contrasting gas-phase reactivity of 2-(2-alkenylpyrrol-1-yl)phenoxyl and thiophenoxyl radicals.
The pyrrolylacrylates 9 and 10 were synthesised and subjected to flash vacuum pyrolysis (FVP) at 650-700 degrees C to generate the radicals 11 and 18, respectively. The phenoxyl 11 underwent hydrogen capture to give a mixture of the phenol 12 and the pyrrolobenzoxazine 13 in low yields, which were also obtained by a Wittig reaction of the 2-formylpyrrole 14. The thiophenoxyl 18 gave a single major product in 41% yield which was identified as the pyrrolo[1,2-a]quinoline 17 by a sequence of NMR experiments. A mechanism for the formation of 17 by a rearrangement-sulfur extrusion sequence is proposed.
Cadogan
J I G
JI
Department of Chemistry, University of Wales Swansea, UK.
Hewage
Chandralal M
CM
McNab
Hamish
H
Macpherson
Andrew D
AD
Nicolson
Iain S
IS
Reed
David
D
Sadler
Ian H
IH