Lactone, 11. Mitt. Synthese von 4.9-Dihydropyrano[3.4-b]indol-1(3H)-onen aus α-Ethoxalyl-γ-lactonen

Lactones, XI: Syntheses of 4.9-Dihydropyrano[3.4-b]-indol-1(3H)-ones from α-Ethoxalyl-γ-lactones Cleavage and decarboxylation of the α-ethoxalyl-γ-lactones 1a-d followed by treatment with phenylhy-drazines yield the hydrazones 4a-l , which can be rearranged to the indololactones 5a-m. Starting from the δ-lactones 6 and 10 , the same reactions lead to indoles without lactone ring closure.