Methylene meldrums acid derivatives of indoxyl and their cyclization reactions under flash vacuum pyrolysis conditions
Pure indoxyl can be obtained in 75% yield by flash vacuum pyrolysis (FVP) of 2′-azidoacetophenone at 650 °C. Reaction of indoxyl with methoxymethylene Meldrums acid takes place at the 1-position, and FVP of the resulting derivative provides 1-hydroxy-9H-pyrrolo[1,2-a]indol-9-one (54%). FVP of the isomeric 2-methylene compound gives pyrano[3,2-b]indol-2(5H)-one (42%). Georg Thieme Verlag Stuttgart · New York.