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9. Iodonium- und pyridiniumylides of malonylheterocycles (Ylides of heterocycles II)
Kappe Th., Korbuly G., Stadlbauer W., Chem. Ber. 111, 3857-3866 (1978)

Abstract: The reaction of malonyl heterocycles such as 4-hydroxycoumarin (1a or -carbostyril (1b with (diacetoxyiodo)bewnzenes 2 gave the iodonium ylides 3 in good yield. Acid-catalyzed treatment of 3 with pyridine or isoquinoline leads to the corresponding ylides 4, while 3 rearranges to 4-aryloxy-3-iodo compounds 5 under the same conditions in the absence of acids. Reductive deiodination of 5 yields the 4-aryloxy compounds 6. By photocyclization of 5a and 6a react to coumestan (8). With HCl 3 is converted into 3-chloro-4-hydroxy- carbostyril (7).

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